92 files changed, 3352 insertions, 151 deletions

diff --git a/src/api/burn/WixToolset.Mba.Core/IPackageInfo.cs b/src/api/burn/WixToolset.Mba.Core/IPackageInfo.cs
index ee3be820..c6285f03 100644
--- a/src/api/burn/WixToolset.Mba.Core/IPackageInfo.cs
+++ b/src/api/burn/WixToolset.Mba.Core/IPackageInfo.cs
@@ -68,6 +68,11 @@ namespace WixToolset.Mba.Core
         string PrereqLicenseUrl { get; }
 
         /// <summary>
+        /// See <see cref="PrimaryPackageType"/>
+        /// </summary>
+        PrimaryPackageType PrimaryPackageType { get; }
+
+        /// <summary>
         /// 
         /// </summary>
         string ProductCode { get; }
diff --git a/src/api/burn/WixToolset.Mba.Core/PackageInfo.cs b/src/api/burn/WixToolset.Mba.Core/PackageInfo.cs
index e400cbe4..3fa1b49e 100644
--- a/src/api/burn/WixToolset.Mba.Core/PackageInfo.cs
+++ b/src/api/burn/WixToolset.Mba.Core/PackageInfo.cs
@@ -64,6 +64,37 @@ namespace WixToolset.Mba.Core
     }
 
     /// <summary>
+    /// Metadata for BAs like WixInternalUIBootstrapperApplication that only support one main package.
+    /// </summary>
+    public enum PrimaryPackageType
+    {
+        /// <summary>
+        /// Not a primary package.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// The default package if no architecture specific package is available for the current architecture.
+        /// </summary>
+        Default,
+
+        /// <summary>
+        /// The package to use on x86 machines.
+        /// </summary>
+        X86,
+
+        /// <summary>
+        /// The package to use on x64 machines.
+        /// </summary>
+        X64,
+
+        /// <summary>
+        /// The package to use on ARM64 machines.
+        /// </summary>
+        ARM64,
+    }
+
+    /// <summary>
     /// Default implementation of <see cref="IPackageInfo"/>.
     /// </summary>
     public class PackageInfo : IPackageInfo
@@ -117,6 +148,9 @@ namespace WixToolset.Mba.Core
         public string PrereqLicenseUrl { get; internal set; }
 
         /// <inheritdoc/>
+        public PrimaryPackageType PrimaryPackageType { get; internal set; }
+
+        /// <inheritdoc/>
         public object CustomData { get; set; }
 
         internal PackageInfo() { }
diff --git a/src/api/burn/balutil/balinfo.cpp b/src/api/burn/balutil/balinfo.cpp
index 5832281f..52a7f911 100644
--- a/src/api/burn/balutil/balinfo.cpp
+++ b/src/api/burn/balutil/balinfo.cpp
@@ -529,6 +529,33 @@ static HRESULT ParseBalPackageInfoFromXml(
         hr = XmlGetAttributeEx(pNode, L"DisplayInternalUICondition", &pPackage->sczDisplayInternalUICondition);
         ExitOnOptionalXmlQueryFailure(hr, fXmlFound, "Failed to get DisplayInternalUICondition setting for package.");
 
+        hr = XmlGetAttributeEx(pNode, L"PrimaryPackageType", &scz);
+        ExitOnOptionalXmlQueryFailure(hr, fXmlFound, "Failed to get PrimaryPackageType setting for package.");
+
+        if (fXmlFound)
+        {
+            if (CSTR_EQUAL == ::CompareStringW(LOCALE_INVARIANT, 0, scz, -1, L"default", -1))
+            {
+                pPackage->primaryPackageType = BAL_INFO_PRIMARY_PACKAGE_TYPE_DEFAULT;
+            }
+            else if (CSTR_EQUAL == ::CompareStringW(LOCALE_INVARIANT, 0, scz, -1, L"x86", -1))
+            {
+                pPackage->primaryPackageType = BAL_INFO_PRIMARY_PACKAGE_TYPE_X86;
+            }
+            else if (CSTR_EQUAL == ::CompareStringW(LOCALE_INVARIANT, 0, scz, -1, L"x64", -1))
+            {
+                pPackage->primaryPackageType = BAL_INFO_PRIMARY_PACKAGE_TYPE_X64;
+            }
+            else if (CSTR_EQUAL == ::CompareStringW(LOCALE_INVARIANT, 0, scz, -1, L"arm64", -1))
+            {
+                pPackage->primaryPackageType = BAL_INFO_PRIMARY_PACKAGE_TYPE_ARM64;
+            }
+            else
+            {
+                ExitWithRootFailure(hr, E_INVALIDARG, "Invalid value for WixBalPackageInfo/@PrimaryPackageType: %ls", scz);
+            }
+        }
+
         ReleaseNullObject(pNode);
     }
     ExitOnFailure(hr, "Failed to parse all WixBalPackageInfo elements.");
diff --git a/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h b/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
index aa1ca56f..c3223bee 100644
--- a/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
+++ b/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
@@ -451,8 +451,8 @@ public: // IBootstrapperApplication
         __in BOOTSTRAPPER_ERROR_TYPE errorType,
         __in_z LPCWSTR wzPackageId,
         __in DWORD dwCode,
-        __in_z LPCWSTR /*wzError*/,
-        __in DWORD /*dwUIHint*/,
+        __in_z LPCWSTR wzError,
+        __in DWORD dwUIHint,
         __in DWORD /*cData*/,
         __in_ecount_z_opt(cData) LPCWSTR* /*rgwzData*/,
         __in int /*nRecommendation*/,
@@ -461,7 +461,15 @@ public: // IBootstrapperApplication
     {
         BalRetryErrorOccurred(wzPackageId, dwCode);
 
-        if (CheckCanceled())
+        if (BOOTSTRAPPER_DISPLAY_EMBEDDED == m_display)
+        {
+            HRESULT hr = m_pEngine->SendEmbeddedError(dwCode, wzError, dwUIHint, pResult);
+            if (FAILED(hr))
+            {
+                *pResult = IDERROR;
+            }
+        }
+        else if (CheckCanceled())
         {
             *pResult = IDCANCEL;
         }
diff --git a/src/api/burn/balutil/inc/balinfo.h b/src/api/burn/balutil/inc/balinfo.h
index cd61f34d..818ff5ef 100644
--- a/src/api/burn/balutil/inc/balinfo.h
+++ b/src/api/burn/balutil/inc/balinfo.h
@@ -20,6 +20,15 @@ typedef enum BAL_INFO_PACKAGE_TYPE
     BAL_INFO_PACKAGE_TYPE_BUNDLE_CHAIN,
 } BAL_INFO_PACKAGE_TYPE;
 
+typedef enum _BAL_INFO_PRIMARY_PACKAGE_TYPE
+{
+    BAL_INFO_PRIMARY_PACKAGE_TYPE_NONE,
+    BAL_INFO_PRIMARY_PACKAGE_TYPE_DEFAULT,
+    BAL_INFO_PRIMARY_PACKAGE_TYPE_X86,
+    BAL_INFO_PRIMARY_PACKAGE_TYPE_X64,
+    BAL_INFO_PRIMARY_PACKAGE_TYPE_ARM64,
+} BAL_INFO_PRIMARY_PACKAGE_TYPE;
+
 typedef enum _BAL_INFO_RESTART
 {
     BAL_INFO_RESTART_UNKNOWN,
@@ -54,6 +63,7 @@ typedef struct _BAL_INFO_PACKAGE
     BOOL fPrereqPackage;
     LPWSTR sczPrereqLicenseFile;
     LPWSTR sczPrereqLicenseUrl;
+    BAL_INFO_PRIMARY_PACKAGE_TYPE primaryPackageType;
     LPVOID pvCustomData;
 } BAL_INFO_PACKAGE;
 
diff --git a/src/api/wix/WixToolset.Data/Burn/BurnConstants.cs b/src/api/wix/WixToolset.Data/Burn/BurnConstants.cs
index 1ecccbd2..8eeb030b 100644
--- a/src/api/wix/WixToolset.Data/Burn/BurnConstants.cs
+++ b/src/api/wix/WixToolset.Data/Burn/BurnConstants.cs
@@ -14,6 +14,9 @@ namespace WixToolset.Data.Burn
         public const string BundleExtensionDataWixOutputStreamName = "wix-bextdata";
         public const string BootstrapperApplicationDataWixOutputStreamName = "wix-badata.xml";
 
+        public const string BootstrapperApplicationDataNamespace = "http://wixtoolset.org/schemas/v4/BootstrapperApplicationData";
+        public const string BundleExtensionDataNamespace = "http://wixtoolset.org/schemas/v4/BundleExtensionData";
+
         public const string BootstrapperApplicationDataSymbolDefinitionTag = "WixBootstrapperApplicationData";
         public const string BundleExtensionSearchSymbolDefinitionTag = "WixBundleExtensionSearch";
 
diff --git a/src/burn/engine/core.cpp b/src/burn/engine/core.cpp
index 90bbc8f6..bfd979de 100644
--- a/src/burn/engine/core.cpp
+++ b/src/burn/engine/core.cpp
@@ -447,9 +447,6 @@ extern "C" HRESULT CorePlan(
     BURN_PACKAGE* pForwardCompatibleBundlePackage = NULL;
     BOOL fContinuePlanning = TRUE; // assume we won't skip planning due to dependencies.
 
-    hr = PlanSetVariables(action, &pEngineState->variables);
-    ExitOnFailure(hr, "Failed to update action.");
-
     LogId(REPORT_STANDARD, MSG_PLAN_BEGIN, pEngineState->packages.cPackages, LoggingBurnActionToString(action));
 
     fPlanBegan = TRUE;
@@ -469,6 +466,9 @@ extern "C" HRESULT CorePlan(
     pEngineState->fPlanned = FALSE;
     PlanReset(&pEngineState->plan, &pEngineState->variables, &pEngineState->containers, &pEngineState->packages, &pEngineState->layoutPayloads);
 
+    hr = PlanSetVariables(action, &pEngineState->variables);
+    ExitOnFailure(hr, "Failed to update action.");
+
     // Remember the overall action state in the plan since it shapes the changes
     // we make everywhere.
     pEngineState->plan.action = action;
diff --git a/src/burn/engine/splashscreen.cpp b/src/burn/engine/splashscreen.cpp
index ff61996f..7ba4e630 100644
--- a/src/burn/engine/splashscreen.cpp
+++ b/src/burn/engine/splashscreen.cpp
@@ -170,7 +170,7 @@ static DWORD WINAPI ThreadProc(
     SPLASHSCREEN_INFO splashScreenInfo = { };
 
     WNDCLASSW wc = { };
-    BOOL fRegistered = TRUE;
+    BOOL fRegistered = FALSE;
 
     BOOL fRet = FALSE;
     MSG msg = { };
diff --git a/src/burn/engine/uithread.cpp b/src/burn/engine/uithread.cpp
index cdd8613c..fe1c21b8 100644
--- a/src/burn/engine/uithread.cpp
+++ b/src/burn/engine/uithread.cpp
@@ -98,7 +98,7 @@ static DWORD WINAPI ThreadProc(
     UITHREAD_INFO info = { };
 
     WNDCLASSW wc = { };
-    BOOL fRegistered = TRUE;
+    BOOL fRegistered = FALSE;
     HWND hWnd = NULL;
 
     BOOL fRet = FALSE;
diff --git a/src/ext/Bal/Bal.wixext.sln b/src/ext/Bal/Bal.wixext.sln
index 9f77d79e..be7149f4 100644
--- a/src/ext/Bal/Bal.wixext.sln
+++ b/src/ext/Bal/Bal.wixext.sln
@@ -9,6 +9,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "bafunctions", "Samples\bafu
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "mbahost", "mbahost\mbahost.vcxproj", "{12C87C77-3547-44F8-8134-29BC915CB19D}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "wixiuiba", "wixiuiba\wixiuiba.vcxproj", "{0F73E566-925C-448D-99CB-3A7F5DF399C8}"
+EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "wixstdba", "wixstdba\wixstdba.vcxproj", "{41085A22-E6AA-4E8B-AB1B-DDEE0DC89DFA}"
 EndProject
 Project("{930C7802-8A8C-48F9-8165-68863BCCD9DD}") = "bal", "wixlib\bal.wixproj", "{3444D952-F21C-496F-AB6B-56435BFD0787}"
@@ -83,6 +85,22 @@ Global
                 {12C87C77-3547-44F8-8134-29BC915CB19D}.Release|x64.Build.0 = Release|x64
                 {12C87C77-3547-44F8-8134-29BC915CB19D}.Release|x86.ActiveCfg = Release|Win32
                 {12C87C77-3547-44F8-8134-29BC915CB19D}.Release|x86.Build.0 = Release|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|Any CPU.ActiveCfg = Debug|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|Any CPU.Build.0 = Debug|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|ARM64.ActiveCfg = Debug|ARM64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|ARM64.Build.0 = Debug|ARM64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|x64.ActiveCfg = Debug|x64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|x64.Build.0 = Debug|x64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|x86.ActiveCfg = Debug|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Debug|x86.Build.0 = Debug|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|Any CPU.ActiveCfg = Release|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|Any CPU.Build.0 = Release|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|ARM64.ActiveCfg = Release|ARM64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|ARM64.Build.0 = Release|ARM64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|x64.ActiveCfg = Release|x64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|x64.Build.0 = Release|x64
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|x86.ActiveCfg = Release|Win32
+                {0F73E566-925C-448D-99CB-3A7F5DF399C8}.Release|x86.Build.0 = Release|Win32
                 {41085A22-E6AA-4E8B-AB1B-DDEE0DC89DFA}.Debug|Any CPU.ActiveCfg = Debug|Win32
                 {41085A22-E6AA-4E8B-AB1B-DDEE0DC89DFA}.Debug|Any CPU.Build.0 = Debug|Win32
                 {41085A22-E6AA-4E8B-AB1B-DDEE0DC89DFA}.Debug|ARM64.ActiveCfg = Debug|ARM64
diff --git a/src/ext/Bal/bal.cmd b/src/ext/Bal/bal.cmd
index 7a005cfe..aedf9b64 100644
--- a/src/ext/Bal/bal.cmd
+++ b/src/ext/Bal/bal.cmd
@@ -14,14 +14,6 @@ nuget restore dnchost\packages.config || exit /b
 msbuild -t:Restore -p:Configuration=%_C% || exit /b
 
 :: Build
-msbuild -p:Configuration=%_C%;Platform=x86 dnchost\dnchost.vcxproj || exit /b
-msbuild -p:Configuration=%_C%;Platform=x64 dnchost\dnchost.vcxproj || exit /b
-msbuild -p:Configuration=%_C%;Platform=ARM64 dnchost\dnchost.vcxproj || exit /b
-
-msbuild -p:Configuration=%_C%;Platform=x86 mbahost\mbahost.vcxproj || exit /b
-msbuild -p:Configuration=%_C%;Platform=x64 mbahost\mbahost.vcxproj || exit /b
-msbuild -p:Configuration=%_C%;Platform=ARM64 mbahost\mbahost.vcxproj || exit /b
-
 msbuild -p:Configuration=%_C%;Platform=x86 test\examples\TestEngine\Example.TestEngine.vcxproj || exit /b
 msbuild -p:Configuration=%_C%;Platform=x64 test\examples\TestEngine\Example.TestEngine.vcxproj || exit /b
 msbuild -p:Configuration=%_C%;Platform=ARM64 test\examples\TestEngine\Example.TestEngine.vcxproj || exit /b
diff --git a/src/ext/Bal/dnchost/dnchost.cpp b/src/ext/Bal/dnchost/dnchost.cpp
index cdf204fb..8faf292c 100644
--- a/src/ext/Bal/dnchost/dnchost.cpp
+++ b/src/ext/Bal/dnchost/dnchost.cpp
@@ -110,18 +110,18 @@ extern "C" HRESULT WINAPI BootstrapperApplicationCreate(
     {
         if (DNCHOSTTYPE_SCD == vstate.type)
         {
-            vstate.prereqData.hrHostInitialization = E_DNCHOST_SCD_RUNTIME_FAILURE;
+            vstate.prereqData.hrFatalError = E_DNCHOST_SCD_RUNTIME_FAILURE;
             BalLogError(hr, "The self-contained .NET Core runtime failed to load. This is an unrecoverable error.");
         }
         else if (vstate.prereqData.fCompleted)
         {
             hr = E_PREREQBA_INFINITE_LOOP;
             BalLogError(hr, "The prerequisites were already installed. The bootstrapper application will not be reloaded to prevent an infinite loop.");
-            vstate.prereqData.hrHostInitialization = hr;
+            vstate.prereqData.hrFatalError = hr;
         }
         else
         {
-            vstate.prereqData.hrHostInitialization = S_OK;
+            vstate.prereqData.hrFatalError = S_OK;
         }
         BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "Loading prerequisite bootstrapper application because .NET Core host could not be loaded, error: 0x%08x.", hr);
 
@@ -233,6 +233,8 @@ static HRESULT LoadDncConfiguration(
         BalExitOnOptionalXmlQueryFailure(hr, fXmlFound, "Failed to get AlwaysInstallPrereqs value.");
     }
 
+    pState->prereqData.fPerformHelp = !pState->prereqData.fAlwaysInstallPrereqs;
+
     pState->type = DNCHOSTTYPE_FDD;
 
     hr = XmlSelectSingleNode(pixdManifest, L"/BootstrapperApplicationData/WixDncOptions", &pixnHost);
diff --git a/src/ext/Bal/mbahost/mbahost.cpp b/src/ext/Bal/mbahost/mbahost.cpp
index 0b89fc58..5edbe376 100644
--- a/src/ext/Bal/mbahost/mbahost.cpp
+++ b/src/ext/Bal/mbahost/mbahost.cpp
@@ -144,17 +144,17 @@ extern "C" HRESULT WINAPI BootstrapperApplicationCreate(
         if (E_MBAHOST_NET452_ON_WIN7RTM == hr)
         {
             BalLogError(hr, "The Burn engine cannot run with an MBA under the .NET 4 CLR on Windows 7 RTM with .NET 4.5.2 (or greater) installed.");
-            vstate.prereqData.hrHostInitialization = hr;
+            vstate.prereqData.hrFatalError = hr;
         }
         else if (vstate.prereqData.fCompleted)
         {
             hr = E_PREREQBA_INFINITE_LOOP;
             BalLogError(hr, "The prerequisites were already installed. The bootstrapper application will not be reloaded to prevent an infinite loop.");
-            vstate.prereqData.hrHostInitialization = hr;
+            vstate.prereqData.hrFatalError = hr;
         }
         else
         {
-            vstate.prereqData.hrHostInitialization = S_OK;
+            vstate.prereqData.hrFatalError = S_OK;
         }
 
         BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "Loading prerequisite bootstrapper application because managed host could not be loaded, error: 0x%08x.", hr);
@@ -306,6 +306,8 @@ static HRESULT LoadMbaConfiguration(
         BalExitOnOptionalXmlQueryFailure(hr, fXmlFound, "Failed to get AlwaysInstallPrereqs value.");
     }
 
+    pState->prereqData.fPerformHelp = !pState->prereqData.fAlwaysInstallPrereqs;
+
 LExit:
     ReleaseObject(pixnHost);
     ReleaseObject(pixdManifest);
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/BalExtensionFixture.cs b/src/ext/Bal/test/WixToolsetTest.Bal/BalExtensionFixture.cs
index d8197467..79e96316 100644
--- a/src/ext/Bal/test/WixToolsetTest.Bal/BalExtensionFixture.cs
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/BalExtensionFixture.cs
@@ -143,6 +143,12 @@ namespace WixToolsetTest.Bal
                 {
                     "<WixMbaPrereqOptions AlwaysInstallPrereqs='1' />",
                 }, wixMbaPrereqOptionsElements);
+
+                var wixMbaPrereqInformationElements = extractResult.GetBADataTestXmlLines("/ba:BootstrapperApplicationData/ba:WixMbaPrereqInformation");
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "<WixMbaPrereqInformation PackageId='wixnative.exe' />",
+                }, wixMbaPrereqInformationElements);
             }
         }
 
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/InternalUIBAFixture.cs b/src/ext/Bal/test/WixToolsetTest.Bal/InternalUIBAFixture.cs
new file mode 100644
index 00000000..dba78da4
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/InternalUIBAFixture.cs
@@ -0,0 +1,474 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolsetTest.Bal
+{
+    using System;
+    using System.IO;
+    using System.Linq;
+    using WixBuildTools.TestSupport;
+    using WixToolset.Core.TestPackage;
+    using Xunit;
+
+    public class InternalUIBAFixture
+    {
+        [Fact]
+        public void CanBuildUsingWixIuiBa()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+                var baFolderPath = Path.Combine(baseFolder, "ba");
+                var extractFolderPath = Path.Combine(baseFolder, "extract");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "SinglePrimaryPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+                compileResult.AssertSuccess();
+
+                Assert.True(File.Exists(bundleFile));
+
+                var extractResult = BundleExtractor.ExtractBAContainer(null, bundleFile, baFolderPath, extractFolderPath);
+                extractResult.AssertSuccess();
+
+                var balPackageInfos = extractResult.GetBADataTestXmlLines("/ba:BootstrapperApplicationData/ba:WixBalPackageInfo");
+                WixAssert.CompareLineByLine(new string[]
+                {
+                    "<WixBalPackageInfo PackageId='test.msi' PrimaryPackageType='default' />",
+                }, balPackageInfos);
+
+                Assert.True(File.Exists(Path.Combine(baFolderPath, "mbapreq.thm")));
+                Assert.True(File.Exists(Path.Combine(baFolderPath, "mbapreq.wxl")));
+            }
+        }
+
+        [Fact]
+        public void CanBuildUsingWixIuiBaWithImplicitPrimaryPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+                var baFolderPath = Path.Combine(baseFolder, "ba");
+                var extractFolderPath = Path.Combine(baseFolder, "extract");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "ImplicitPrimaryPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+                compileResult.AssertSuccess();
+
+                Assert.True(File.Exists(bundleFile));
+
+                var extractResult = BundleExtractor.ExtractBAContainer(null, bundleFile, baFolderPath, extractFolderPath);
+                extractResult.AssertSuccess();
+
+                var balPackageInfos = extractResult.GetBADataTestXmlLines("/ba:BootstrapperApplicationData/ba:WixBalPackageInfo");
+                WixAssert.CompareLineByLine(new string[]
+                {
+                    "<WixBalPackageInfo PackageId='test.msi' PrimaryPackageType='default' />",
+                }, balPackageInfos);
+
+                var mbaPrereqInfos = extractResult.GetBADataTestXmlLines("/ba:BootstrapperApplicationData/ba:WixMbaPrereqInformation");
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "<WixMbaPrereqInformation PackageId='wixnative.exe' />",
+                }, mbaPrereqInfos);
+
+                Assert.True(File.Exists(Path.Combine(baFolderPath, "mbapreq.thm")));
+                Assert.True(File.Exists(Path.Combine(baFolderPath, "mbapreq.wxl")));
+            }
+        }
+
+        [Fact]
+        public void CanBuildUsingWixIuiBaWithWarnings()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+                var baFolderPath = Path.Combine(baseFolder, "ba");
+                var extractFolderPath = Path.Combine(baseFolder, "extract");
+
+                var compileResult = WixRunner.Execute(warningsAsErrors: false, new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "IuiBaWarnings.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "WixInternalUIBootstrapperApplication does not support the value of 'force' for Cache on prereq packages. Prereq packages are only cached when they need to be installed.",
+                    "WixInternalUIBootstrapperApplication ignores InstallCondition for the primary package so that the MSI UI is always shown.",
+                    "WixInternalUIBootstrapperApplication ignores DisplayInternalUICondition for the primary package so that the MSI UI is always shown.",
+                    "When using WixInternalUIBootstrapperApplication, all prereq packages should be before the primary package in the chain. The prereq packages are always installed before the primary package.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                compileResult.AssertSuccess();
+
+                Assert.True(File.Exists(bundleFile));
+
+                var extractResult = BundleExtractor.ExtractBAContainer(null, bundleFile, baFolderPath, extractFolderPath);
+                extractResult.AssertSuccess();
+
+                var balPackageInfos = extractResult.GetBADataTestXmlLines("/ba:BootstrapperApplicationData/ba:WixBalPackageInfo");
+                WixAssert.CompareLineByLine(new string[]
+                {
+                    "<WixBalPackageInfo PackageId='test.msi' DisplayInternalUICondition='DISPLAYTEST' PrimaryPackageType='default' />",
+                }, balPackageInfos);
+
+                var mbaPrereqInfos = extractResult.GetBADataTestXmlLines("/ba:BootstrapperApplicationData/ba:WixMbaPrereqInformation");
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "<WixMbaPrereqInformation PackageId='wixnative.exe' />",
+                }, mbaPrereqInfos);
+
+                Assert.True(File.Exists(Path.Combine(baFolderPath, "mbapreq.thm")));
+                Assert.True(File.Exists(Path.Combine(baFolderPath, "mbapreq.wxl")));
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithAllPrereqPackages()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "AllPrereqPackages.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, there must be one package with bal:PrimaryPackageType=\"default\".",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6808, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithImplicitNonMsiPrimaryPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "ImplicitNonMsiPrimaryPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, packages must either be non-permanent and have the bal:PrimaryPackageType attribute, or be permanent and have the bal:PrereqPackage attribute set to 'yes'.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6811, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithImplicitPrimaryPackageEnableFeatureSelection()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "ImplicitPrimaryPackageEnableFeatureSelection.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, packages must either be non-permanent and have the bal:PrimaryPackageType attribute, or be permanent and have the bal:PrereqPackage attribute set to 'yes'.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6811, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithMultipleNonPermanentNonPrimaryPackages()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "MultipleNonPermanentNonPrimaryPackages.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, packages must either be non-permanent and have the bal:PrimaryPackageType attribute, or be permanent and have the bal:PrereqPackage attribute set to 'yes'.",
+                    "When using WixInternalUIBootstrapperApplication, packages must either be non-permanent and have the bal:PrimaryPackageType attribute, or be permanent and have the bal:PrereqPackage attribute set to 'yes'.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6811, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithMultiplePrimaryPackagesOfSameType()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "MultipleDefaultPrimaryPackages.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "There may only be one package in the bundle with PrimaryPackageType of 'default'.",
+                    "The location of the package related to the previous error.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6810, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithNoDefaultPrimaryPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "NoDefaultPrimaryPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, there must be one package with bal:PrimaryPackageType=\"default\".",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6808, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithNonMsiPrimaryPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "NonMsiPrimaryPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, each primary package must be an MsiPackage.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6814, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithNonPermanentPrereqPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "NonPermanentPrereqPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication and bal:PrereqPackage is set to 'yes', the package must be permanent.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6812, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithPermanentPrimaryPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "PermanentPrimaryPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, packages with the bal:PrimaryPackageType attribute must not be permanent.",
+                    "When using WixInternalUIBootstrapperApplication, there must be one package with bal:PrimaryPackageType=\"default\".",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6808, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithPrimaryPackageEnableFeatureSelection()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var bundleFile = Path.Combine(baseFolder, "bin", "test.exe");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "PrimaryPackageEnableFeatureSelection.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-bindpath", TestData.Get(@"TestData\WixStdBa\Data"),
+                    "-o", bundleFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "When using WixInternalUIBootstrapperApplication, primary packages must not have feature selection enabled because it interferes with the user selecting feature through the MSI UI.",
+                    "When using WixInternalUIBootstrapperApplication, there must be one package with bal:PrimaryPackageType=\"default\".",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(6808, compileResult.ExitCode);
+            }
+        }
+
+        [Fact]
+        public void CannotBuildUsingWixIuiBaWithPrimaryPrereqPackage()
+        {
+            using (var fs = new DisposableFileSystem())
+            {
+                var baseFolder = fs.GetFolder();
+                var wixlibFile = Path.Combine(baseFolder, "bin", "test.wixlib");
+                var bundleSourceFolder = TestData.Get(@"TestData\WixIuiBa");
+                var intermediateFolder = Path.Combine(baseFolder, "obj");
+
+                var compileResult = WixRunner.Execute(new[]
+                {
+                    "build",
+                    Path.Combine(bundleSourceFolder, "PrimaryPrereqPackage.wxs"),
+                    "-ext", TestData.Get(@"WixToolset.Bal.wixext.dll"),
+                    "-intermediateFolder", intermediateFolder,
+                    "-o", wixlibFile,
+                });
+
+                WixAssert.CompareLineByLine(new[]
+                {
+                    "The MsiPackage/@PrereqPackage attribute's value, 'yes', cannot be specified with attribute PrimaryPackageType present.",
+                }, compileResult.Messages.Select(m => m.ToString()).ToArray());
+
+                Assert.Equal(193, compileResult.ExitCode);
+            }
+        }
+    }
+}
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/AllPrereqPackages.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/AllPrereqPackages.wxs
new file mode 100644
index 00000000..17f1ee77
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/AllPrereqPackages.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage bal:PrereqPackage="yes" Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" />
+            <MsiPackage bal:PrereqPackage="yes" Permanent="yes" SourceFile="test.msi" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitNonMsiPrimaryPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitNonMsiPrimaryPackage.wxs
new file mode 100644
index 00000000..ca1f9358
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitNonMsiPrimaryPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <MsiPackage SourceFile="test.msi" Permanent="yes" />
+            <ExePackage UninstallArguments="" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitPrimaryPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitPrimaryPackage.wxs
new file mode 100644
index 00000000..16a99e92
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitPrimaryPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" />
+            <MsiPackage SourceFile="test.msi" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitPrimaryPackageEnableFeatureSelection.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitPrimaryPackageEnableFeatureSelection.wxs
new file mode 100644
index 00000000..85b9df65
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/ImplicitPrimaryPackageEnableFeatureSelection.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" />
+            <MsiPackage SourceFile="test.msi" EnableFeatureSelection="yes" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/IuibaWarnings.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/IuibaWarnings.wxs
new file mode 100644
index 00000000..2cf9787d
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/IuibaWarnings.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <MsiPackage SourceFile="test.msi" InstallCondition="INSTALLTEST" bal:DisplayInternalUICondition="DISPLAYTEST" />
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" Cache="force" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/MultipleDefaultPrimaryPackages.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/MultipleDefaultPrimaryPackages.wxs
new file mode 100644
index 00000000..11736fbb
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/MultipleDefaultPrimaryPackages.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{5C7B7C41-B3A9-4FFF-952A-B6D68320B9B4}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <MsiPackage Id="One" SourceFile="test.msi" bal:PrimaryPackageType="default" />
+            <MsiPackage Id="Two" CacheId="dontdothis" SourceFile="test.msi" bal:PrimaryPackageType="default" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/MultipleNonPermanentNonPrimaryPackages.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/MultipleNonPermanentNonPrimaryPackages.wxs
new file mode 100644
index 00000000..c5b923df
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/MultipleNonPermanentNonPrimaryPackages.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage UninstallArguments="" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" />
+            <MsiPackage SourceFile="test.msi" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NoDefaultPrimaryPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NoDefaultPrimaryPackage.wxs
new file mode 100644
index 00000000..7f7528d0
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NoDefaultPrimaryPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" />
+            <MsiPackage bal:PrimaryPackageType="x86" SourceFile="test.msi" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NonMsiPrimaryPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NonMsiPrimaryPackage.wxs
new file mode 100644
index 00000000..a6f93bcb
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NonMsiPrimaryPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{1CD73801-0B08-4B39-B371-00DA49EF715F}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage UninstallArguments="" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" bal:PrimaryPackageType="x86" />
+            <MsiPackage SourceFile="test.msi" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NonPermanentPrereqPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NonPermanentPrereqPackage.wxs
new file mode 100644
index 00000000..a60943b0
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/NonPermanentPrereqPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{5C7B7C41-B3A9-4FFF-952A-B6D68320B9B4}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage UninstallArguments="" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" bal:PrereqPackage="yes" />
+            <MsiPackage SourceFile="test.msi" bal:PrimaryPackageType="default" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PermanentPrimaryPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PermanentPrimaryPackage.wxs
new file mode 100644
index 00000000..43caaf86
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PermanentPrimaryPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{5C7B7C41-B3A9-4FFF-952A-B6D68320B9B4}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" bal:PrereqPackage="yes" />
+            <MsiPackage SourceFile="test.msi" bal:PrimaryPackageType="default" Permanent="yes" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PrimaryPackageEnableFeatureSelection.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PrimaryPackageEnableFeatureSelection.wxs
new file mode 100644
index 00000000..4f1c40dd
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PrimaryPackageEnableFeatureSelection.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{5C7B7C41-B3A9-4FFF-952A-B6D68320B9B4}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" bal:PrereqPackage="yes" />
+            <MsiPackage SourceFile="test.msi" bal:PrimaryPackageType="default" EnableFeatureSelection="yes" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PrimaryPrereqPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PrimaryPrereqPackage.wxs
new file mode 100644
index 00000000..bdb8c470
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/PrimaryPrereqPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{5C7B7C41-B3A9-4FFF-952A-B6D68320B9B4}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" bal:PrereqPackage="yes" />
+            <MsiPackage SourceFile="test.msi" bal:PrimaryPackageType="default" bal:PrereqPackage="yes" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/SinglePrimaryPackage.wxs b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/SinglePrimaryPackage.wxs
new file mode 100644
index 00000000..1e9a87c2
--- /dev/null
+++ b/src/ext/Bal/test/WixToolsetTest.Bal/TestData/WixIuiBa/SinglePrimaryPackage.wxs
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
+     xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+    <Bundle Name="WixIuiBa" Version="1.0.0.0" Manufacturer="Example Corporation" UpgradeCode="{5C7B7C41-B3A9-4FFF-952A-B6D68320B9B4}">
+        <BootstrapperApplication>
+            <bal:WixInternalUIBootstrapperApplication />
+        </BootstrapperApplication>
+        <Chain>
+            <ExePackage Permanent="yes" DetectCondition="none" SourceFile="runtimes\win-x86\native\wixnative.exe" bal:PrereqPackage="yes" />
+            <MsiPackage SourceFile="test.msi" bal:PrimaryPackageType="default" />
+        </Chain>
+    </Bundle>
+</Wix>
diff --git a/src/ext/Bal/wixext/BalBurnBackendExtension.cs b/src/ext/Bal/wixext/BalBurnBackendExtension.cs
index d34c159a..6f615796 100644
--- a/src/ext/Bal/wixext/BalBurnBackendExtension.cs
+++ b/src/ext/Bal/wixext/BalBurnBackendExtension.cs
@@ -5,6 +5,8 @@ namespace WixToolset.Bal
     using System;
     using System.Collections.Generic;
     using System.Linq;
+    using System.Text;
+    using System.Xml;
     using WixToolset.Bal.Symbols;
     using WixToolset.Data;
     using WixToolset.Data.Burn;
@@ -29,12 +31,48 @@ namespace WixToolset.Bal
 
         protected override IReadOnlyCollection<IntermediateSymbolDefinition> SymbolDefinitions => BurnSymbolDefinitions;
 
+        public override bool TryProcessSymbol(IntermediateSection section, IntermediateSymbol symbol)
+        {
+            if (symbol is WixBalPackageInfoSymbol balPackageInfoSymbol)
+            {
+                // There might be a more efficient way to do this,
+                // but this is an easy way to ensure we're creating valid XML.
+                var sb = new StringBuilder();
+                using (var writer = XmlWriter.Create(sb))
+                {
+                    writer.WriteStartElement(symbol.Definition.Name, BurnConstants.BootstrapperApplicationDataNamespace);
+
+                    writer.WriteAttributeString("PackageId", balPackageInfoSymbol.PackageId);
+
+                    if (balPackageInfoSymbol.DisplayInternalUICondition != null)
+                    {
+                        writer.WriteAttributeString("DisplayInternalUICondition", balPackageInfoSymbol.DisplayInternalUICondition);
+                    }
+
+                    if (balPackageInfoSymbol.PrimaryPackageType != BalPrimaryPackageType.None)
+                    {
+                        writer.WriteAttributeString("PrimaryPackageType", balPackageInfoSymbol.PrimaryPackageType.ToString().ToLower());
+                    }
+
+                    writer.WriteEndElement();
+                }
+
+                this.BackendHelper.AddBootstrapperApplicationData(sb.ToString());
+
+                return true;
+            }
+            else
+            {
+                return base.TryProcessSymbol(section, symbol);
+            }
+        }
+
         public override void SymbolsFinalized(IntermediateSection section)
         {
             base.SymbolsFinalized(section);
 
             this.VerifyBalConditions(section);
-            this.VerifyBalPackageInfos(section);
+            this.VerifyDisplayInternalUICondition(section);
             this.VerifyOverridableVariables(section);
 
             var baSymbol = section.Symbols.OfType<WixBootstrapperApplicationDllSymbol>().SingleOrDefault();
@@ -44,24 +82,31 @@ namespace WixToolset.Bal
                 return;
             }
 
+            var isIuiBA = baId.StartsWith("WixInternalUIBootstrapperApplication");
             var isStdBA = baId.StartsWith("WixStandardBootstrapperApplication");
             var isMBA = baId.StartsWith("WixManagedBootstrapperApplicationHost");
             var isDNC = baId.StartsWith("WixDotNetCoreBootstrapperApplicationHost");
             var isSCD = isDNC && this.VerifySCD(section);
 
+            if (isIuiBA)
+            {
+                // This needs to happen before VerifyPrereqPackages because it can add prereq packages.
+                this.VerifyPrimaryPackages(section);
+            }
+
             if (isDNC)
             {
                 this.FinalizeBAFactorySymbol(section);
             }
 
-            if (isStdBA || isMBA || isDNC)
+            if (isIuiBA || isStdBA || isMBA || isDNC)
             {
                 this.VerifyBAFunctions(section);
             }
 
-            if (isMBA || (isDNC && !isSCD))
+            if (isIuiBA || isMBA || (isDNC && !isSCD))
             {
-                this.VerifyPrereqPackages(section, isDNC);
+                this.VerifyPrereqPackages(section, isDNC, isIuiBA);
             }
         }
 
@@ -133,12 +178,241 @@ namespace WixToolset.Bal
             }
         }
 
-        private void VerifyBalPackageInfos(IntermediateSection section)
+        private void VerifyDisplayInternalUICondition(IntermediateSection section)
+        {
+            foreach (var balPackageInfoSymbol in section.Symbols.OfType<WixBalPackageInfoSymbol>().ToList())
+            {
+                if (balPackageInfoSymbol.DisplayInternalUICondition != null)
+                {
+                    this.BackendHelper.ValidateBundleCondition(balPackageInfoSymbol.SourceLineNumbers, "*Package", "bal:DisplayInternalUICondition", balPackageInfoSymbol.DisplayInternalUICondition, BundleConditionPhase.Plan);
+                }
+            }
+        }
+
+        private void VerifyPrimaryPackages(IntermediateSection section)
+        {
+            WixBalPackageInfoSymbol defaultPrimaryPackage = null;
+            WixBalPackageInfoSymbol x86PrimaryPackage = null;
+            WixBalPackageInfoSymbol x64PrimaryPackage = null;
+            WixBalPackageInfoSymbol arm64PrimaryPackage = null;
+            var nonPermanentNonPrimaryPackages = new List<WixBundlePackageSymbol>();
+
+            var balPackageInfoSymbolsByPackageId = section.Symbols.OfType<WixBalPackageInfoSymbol>().ToDictionary(x => x.PackageId);
+            var mbaPrereqInfoSymbolsByPackageId = section.Symbols.OfType<WixMbaPrereqInformationSymbol>().ToDictionary(x => x.PackageId);
+            var msiPackageSymbolsByPackageId = section.Symbols.OfType<WixBundleMsiPackageSymbol>().ToDictionary(x => x.Id.Id);
+            var packageSymbols = section.Symbols.OfType<WixBundlePackageSymbol>().ToList();
+            foreach (var packageSymbol in packageSymbols)
+            {
+                var packageId = packageSymbol.Id?.Id;
+                var isPrereq = false;
+                var primaryPackageType = BalPrimaryPackageType.None;
+
+                if (mbaPrereqInfoSymbolsByPackageId.TryGetValue(packageId, out var _))
+                {
+                    isPrereq = true;
+                }
+
+                if (balPackageInfoSymbolsByPackageId.TryGetValue(packageId, out var balPackageInfoSymbol))
+                {
+                    primaryPackageType = balPackageInfoSymbol.PrimaryPackageType;
+                }
+
+                if (packageSymbol.Permanent)
+                {
+                    if (primaryPackageType != BalPrimaryPackageType.None)
+                    {
+                        this.Messaging.Write(BalErrors.IuibaPermanentPrimaryPackageType(packageSymbol.SourceLineNumbers));
+                    }
+                    else
+                    {
+                        if (!isPrereq)
+                        {
+                            var prereqInfoSymbol = section.AddSymbol(new WixMbaPrereqInformationSymbol(packageSymbol.SourceLineNumbers, new Identifier(AccessModifier.Global, packageId))
+                            {
+                                PackageId = packageId,
+                            });
+
+                            mbaPrereqInfoSymbolsByPackageId.Add(packageId, prereqInfoSymbol);
+                        }
+
+                        this.VerifyIuibaPrereqPackage(packageSymbol);
+                    }
+                }
+                else
+                {
+                    if (isPrereq)
+                    {
+                        if (primaryPackageType == BalPrimaryPackageType.None)
+                        {
+                            this.Messaging.Write(BalErrors.IuibaNonPermanentPrereqPackage(packageSymbol.SourceLineNumbers));
+                        }
+                        else
+                        {
+                            this.Messaging.Write(ErrorMessages.IllegalAttributeValueWithOtherAttribute(
+                                packageSymbol.SourceLineNumbers,
+                                packageSymbol.Type + "Package",
+                                "PrereqPackage",
+                                "yes",
+                                "PrimaryPackageType"));
+                        }
+                    }
+                    else if (primaryPackageType == BalPrimaryPackageType.None)
+                    {
+                        nonPermanentNonPrimaryPackages.Add(packageSymbol);
+                    }
+                    else if (packageSymbol.Type != WixBundlePackageType.Msi)
+                    {
+                        this.Messaging.Write(BalErrors.IuibaNonMsiPrimaryPackage(packageSymbol.SourceLineNumbers));
+                    }
+                    else if (!msiPackageSymbolsByPackageId.TryGetValue(packageId, out var msiPackageSymbol))
+                    {
+                        throw new WixException($"Missing WixBundleMsiPackageSymbol for package '{packageId}'");
+                    }
+                    else if (msiPackageSymbol.EnableFeatureSelection)
+                    {
+                        this.Messaging.Write(BalErrors.IuibaPrimaryPackageEnableFeatureSelection(packageSymbol.SourceLineNumbers));
+                    }
+                    else
+                    {
+                        if (primaryPackageType == BalPrimaryPackageType.Default)
+                        {
+                            if (defaultPrimaryPackage == null)
+                            {
+                                defaultPrimaryPackage = balPackageInfoSymbol;
+                            }
+                            else
+                            {
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType(balPackageInfoSymbol.SourceLineNumbers, "default"));
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType2(defaultPrimaryPackage.SourceLineNumbers));
+                            }
+                        }
+                        else if (balPackageInfoSymbol.PrimaryPackageType == BalPrimaryPackageType.X86)
+                        {
+                            if (x86PrimaryPackage == null)
+                            {
+                                x86PrimaryPackage = balPackageInfoSymbol;
+                            }
+                            else
+                            {
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType(balPackageInfoSymbol.SourceLineNumbers, "x86"));
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType2(x86PrimaryPackage.SourceLineNumbers));
+                            }
+                        }
+                        else if (balPackageInfoSymbol.PrimaryPackageType == BalPrimaryPackageType.X64)
+                        {
+                            if (x64PrimaryPackage == null)
+                            {
+                                x64PrimaryPackage = balPackageInfoSymbol;
+                            }
+                            else
+                            {
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType(balPackageInfoSymbol.SourceLineNumbers, "x64"));
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType2(x64PrimaryPackage.SourceLineNumbers));
+                            }
+                        }
+                        else if (balPackageInfoSymbol.PrimaryPackageType == BalPrimaryPackageType.ARM64)
+                        {
+                            if (arm64PrimaryPackage == null)
+                            {
+                                arm64PrimaryPackage = balPackageInfoSymbol;
+                            }
+                            else
+                            {
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType(balPackageInfoSymbol.SourceLineNumbers, "arm64"));
+                                this.Messaging.Write(BalErrors.MultiplePrimaryPackageType2(arm64PrimaryPackage.SourceLineNumbers));
+                            }
+                        }
+                        else
+                        {
+                            throw new NotImplementedException();
+                        }
+
+                        this.VerifyIuibaPrimaryPackage(packageSymbol, balPackageInfoSymbol);
+                    }
+                }
+            }
+
+            if (defaultPrimaryPackage == null && nonPermanentNonPrimaryPackages.Count == 1)
+            {
+                var packageSymbol = nonPermanentNonPrimaryPackages[0];
+
+                if (packageSymbol.Type == WixBundlePackageType.Msi)
+                {
+                    var packageId = packageSymbol.Id?.Id;
+                    var msiPackageSymbol = section.Symbols.OfType<WixBundleMsiPackageSymbol>()
+                                                  .SingleOrDefault(x => x.Id.Id == packageId);
+                    if (!msiPackageSymbol.EnableFeatureSelection)
+                    {
+                        if (!balPackageInfoSymbolsByPackageId.TryGetValue(packageId, out var balPackageInfoSymbol))
+                        {
+                            balPackageInfoSymbol = section.AddSymbol(new WixBalPackageInfoSymbol(packageSymbol.SourceLineNumbers, new Identifier(AccessModifier.Global, packageId))
+                            {
+                                PackageId = packageId,
+                            });
+
+                            balPackageInfoSymbolsByPackageId.Add(packageId, balPackageInfoSymbol);
+                        }
+
+                        balPackageInfoSymbol.PrimaryPackageType = BalPrimaryPackageType.Default;
+                        defaultPrimaryPackage = balPackageInfoSymbol;
+                        nonPermanentNonPrimaryPackages.RemoveAt(0);
+
+                        this.VerifyIuibaPrimaryPackage(packageSymbol, balPackageInfoSymbol);
+                    }
+                }
+            }
+
+            if (nonPermanentNonPrimaryPackages.Count > 0)
+            {
+                foreach (var packageSymbol in nonPermanentNonPrimaryPackages)
+                {
+                    this.Messaging.Write(BalErrors.IuibaNonPermanentNonPrimaryPackage(packageSymbol.SourceLineNumbers));
+                }
+            }
+            else if (defaultPrimaryPackage == null)
+            {
+                this.Messaging.Write(BalErrors.MissingIUIPrimaryPackage());
+            }
+            else
+            {
+                var foundPrimaryPackage = false;
+                var chainPackageGroupSymbols = section.Symbols.OfType<WixGroupSymbol>()
+                                                              .Where(x => x.ChildType == ComplexReferenceChildType.Package &&
+                                                                          x.ParentType == ComplexReferenceParentType.PackageGroup &&
+                                                                          x.ParentId == BurnConstants.BundleChainPackageGroupId);
+                foreach (var chainPackageGroupSymbol in chainPackageGroupSymbols)
+                {
+                    var packageId = chainPackageGroupSymbol.ChildId;
+                    if (balPackageInfoSymbolsByPackageId.TryGetValue(packageId, out var balPackageInfo) && balPackageInfo.PrimaryPackageType != BalPrimaryPackageType.None)
+                    {
+                        foundPrimaryPackage = true;
+                    }
+                    else if (foundPrimaryPackage && mbaPrereqInfoSymbolsByPackageId.TryGetValue(packageId, out var mbaPrereqInformationSymbol))
+                    {
+                        this.Messaging.Write(BalWarnings.IuibaPrereqPackageAfterPrimaryPackage(chainPackageGroupSymbol.SourceLineNumbers));
+                    }
+                }
+            }
+        }
+
+        private void VerifyIuibaPrereqPackage(WixBundlePackageSymbol packageSymbol)
+        {
+            if (packageSymbol.Cache == BundleCacheType.Force)
+            {
+                this.Messaging.Write(BalWarnings.IuibaForceCachePrereq(packageSymbol.SourceLineNumbers));
+            }
+        }
+
+        private void VerifyIuibaPrimaryPackage(WixBundlePackageSymbol packageSymbol, WixBalPackageInfoSymbol balPackageInfoSymbol)
         {
-            var balPackageInfoSymbols = section.Symbols.OfType<WixBalPackageInfoSymbol>().ToList();
-            foreach (var balPackageInfoSymbol in balPackageInfoSymbols)
+            if (packageSymbol.InstallCondition != null)
+            {
+                this.Messaging.Write(BalWarnings.IuibaPrimaryPackageInstallCondition(packageSymbol.SourceLineNumbers));
+            }
+
+            if (balPackageInfoSymbol.DisplayInternalUICondition != null)
             {
-                this.BackendHelper.ValidateBundleCondition(balPackageInfoSymbol.SourceLineNumbers, "*Package", "bal:DisplayInternalUICondition", balPackageInfoSymbol.DisplayInternalUICondition, BundleConditionPhase.Plan);
+                this.Messaging.Write(BalWarnings.IuibaPrimaryPackageDisplayInternalUICondition(packageSymbol.SourceLineNumbers));
             }
         }
 
@@ -161,10 +435,10 @@ namespace WixToolset.Bal
             }
         }
 
-        private void VerifyPrereqPackages(IntermediateSection section, bool isDNC)
+        private void VerifyPrereqPackages(IntermediateSection section, bool isDNC, bool isIuiBA)
         {
             var prereqInfoSymbols = section.Symbols.OfType<WixMbaPrereqInformationSymbol>().ToList();
-            if (prereqInfoSymbols.Count == 0)
+            if (!isIuiBA && prereqInfoSymbols.Count == 0)
             {
                 var message = isDNC ? BalErrors.MissingDNCPrereq() : BalErrors.MissingMBAPrereq();
                 this.Messaging.Write(message);
diff --git a/src/ext/Bal/wixext/BalCompiler.cs b/src/ext/Bal/wixext/BalCompiler.cs
index 1721f252..bc2ba861 100644
--- a/src/ext/Bal/wixext/BalCompiler.cs
+++ b/src/ext/Bal/wixext/BalCompiler.cs
@@ -16,7 +16,8 @@ namespace WixToolset.Bal
     /// </summary>
     public sealed class BalCompiler : BaseCompilerExtension
     {
-        private readonly Dictionary<string, WixMbaPrereqInformationSymbol> prereqInfoSymbolsByPackageId;
+        private readonly Dictionary<string, WixBalPackageInfoSymbol> packageInfoSymbolsByPackageId = new Dictionary<string, WixBalPackageInfoSymbol>();
+        private readonly Dictionary<string, WixMbaPrereqInformationSymbol> prereqInfoSymbolsByPackageId = new Dictionary<string, WixMbaPrereqInformationSymbol>();
 
         private enum WixDotNetCoreBootstrapperApplicationHostTheme
         {
@@ -32,6 +33,13 @@ namespace WixToolset.Bal
             Standard,
         }
 
+        private enum WixInternalUIBootstrapperApplicationTheme
+        {
+            Unknown,
+            None,
+            Standard,
+        }
+
         private enum WixStandardBootstrapperApplicationTheme
         {
             Unknown,
@@ -43,14 +51,6 @@ namespace WixToolset.Bal
             RtfLicense,
         }
 
-        /// <summary>
-        /// Instantiate a new BalCompiler.
-        /// </summary>
-        public BalCompiler()
-        {
-            this.prereqInfoSymbolsByPackageId = new Dictionary<string, WixMbaPrereqInformationSymbol>();
-        }
-
         public override XNamespace Namespace => "http://wixtoolset.org/schemas/v4/wxs/bal";
 
         /// <summary>
@@ -83,6 +83,9 @@ namespace WixToolset.Bal
                 case "BootstrapperApplication":
                     switch (element.Name.LocalName)
                     {
+                        case "WixInternalUIBootstrapperApplication":
+                            this.ParseWixInternalUIBootstrapperApplicationElement(intermediate, section, element);
+                            break;
                         case "WixStandardBootstrapperApplication":
                             this.ParseWixStandardBootstrapperApplicationElement(intermediate, section, element);
                             break;
@@ -113,7 +116,6 @@ namespace WixToolset.Bal
         public override void ParseAttribute(Intermediate intermediate, IntermediateSection section, XElement parentElement, XAttribute attribute, IDictionary<string, string> context)
         {
             var sourceLineNumbers = this.ParseHelper.GetSourceLineNumbers(parentElement);
-            WixMbaPrereqInformationSymbol prereqInfo;
 
             switch (parentElement.Name.LocalName)
             {
@@ -137,42 +139,63 @@ namespace WixToolset.Bal
                                     case "MsiPackage":
                                     case "MspPackage":
                                         var displayInternalUICondition = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attribute);
-                                        section.AddSymbol(new WixBalPackageInfoSymbol(sourceLineNumbers, new Identifier(AccessModifier.Global, packageId))
-                                        {
-                                            PackageId = packageId,
-                                            DisplayInternalUICondition = displayInternalUICondition,
-                                        });
+                                        var packageInfo = this.GetBalPackageInfoSymbol(section, sourceLineNumbers, packageId);
+                                        packageInfo.DisplayInternalUICondition = displayInternalUICondition;
                                         break;
                                     default:
                                         this.ParseHelper.UnexpectedAttribute(parentElement, attribute);
                                         break;
                                 }
                                 break;
-                            case "PrereqLicenseFile":
-
-                                if (!this.prereqInfoSymbolsByPackageId.TryGetValue(packageId, out prereqInfo))
+                            case "PrimaryPackageType":
+                            {
+                                var primaryPackageType = BalPrimaryPackageType.None;
+                                var primaryPackageTypeValue = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attribute);
+                                switch (primaryPackageTypeValue)
                                 {
-                                    // at the time the extension attribute is parsed, the compiler might not yet have
-                                    // parsed the PrereqPackage attribute, so we need to get it directly from the parent element.
-                                    var prereqPackage = parentElement.Attribute(this.Namespace + "PrereqPackage");
-
-                                    if (null != prereqPackage && YesNoType.Yes == this.ParseHelper.GetAttributeYesNoValue(sourceLineNumbers, prereqPackage))
-                                    {
-                                        prereqInfo = section.AddSymbol(new WixMbaPrereqInformationSymbol(sourceLineNumbers)
-                                        {
-                                            PackageId = packageId,
-                                        });
-
-                                        this.prereqInfoSymbolsByPackageId.Add(packageId, prereqInfo);
-                                    }
-                                    else
-                                    {
-                                        this.Messaging.Write(BalErrors.AttributeRequiresPrereqPackage(sourceLineNumbers, parentElement.Name.LocalName, "PrereqLicenseFile"));
+                                    case "default":
+                                        primaryPackageType = BalPrimaryPackageType.Default;
+                                        break;
+                                    case "x86":
+                                        primaryPackageType = BalPrimaryPackageType.X86;
+                                        break;
+                                    case "x64":
+                                        primaryPackageType = BalPrimaryPackageType.X64;
+                                        break;
+                                    case "arm64":
+                                        primaryPackageType = BalPrimaryPackageType.ARM64;
+                                        break;
+                                    default:
+                                        this.Messaging.Write(ErrorMessages.IllegalAttributeValue(sourceLineNumbers, parentElement.Name.LocalName, "PrimaryPackageType", primaryPackageTypeValue, "default", "x86", "x64", "arm64"));
                                         break;
-                                    }
                                 }
 
-                                if (null != prereqInfo.LicenseUrl)
+                                // at the time the extension attribute is parsed, the compiler might not yet have
+                                // parsed the PrereqPackage attribute, so we need to get it directly from the parent element.
+                                var prereqPackage = parentElement.Attribute(this.Namespace + "PrereqPackage");
+                                var prereqInfo = this.GetMbaPrereqInformationSymbol(section, sourceLineNumbers, prereqPackage, packageId);
+                                if (prereqInfo != null)
+                                {
+                                    this.Messaging.Write(ErrorMessages.IllegalAttributeValueWithOtherAttribute(sourceLineNumbers, parentElement.Name.LocalName, "PrereqPackage", "yes", "PrimaryPackageType"));
+                                }
+                                else
+                                {
+                                    var packageInfo = this.GetBalPackageInfoSymbol(section, sourceLineNumbers, packageId);
+                                    packageInfo.PrimaryPackageType = primaryPackageType;
+                                }
+                                break;
+                            }
+                            case "PrereqLicenseFile":
+                            {
+                                // at the time the extension attribute is parsed, the compiler might not yet have
+                                // parsed the PrereqPackage attribute, so we need to get it directly from the parent element.
+                                var prereqPackage = parentElement.Attribute(this.Namespace + "PrereqPackage");
+                                var prereqInfo = this.GetMbaPrereqInformationSymbol(section, sourceLineNumbers, prereqPackage, packageId);
+                                if (prereqInfo == null)
+                                {
+                                    this.Messaging.Write(BalErrors.AttributeRequiresPrereqPackage(sourceLineNumbers, parentElement.Name.LocalName, "PrereqLicenseFile"));
+                                }
+                                else if (null != prereqInfo.LicenseUrl)
                                 {
                                     this.Messaging.Write(ErrorMessages.IllegalAttributeWithOtherAttribute(sourceLineNumbers, parentElement.Name.LocalName, "PrereqLicenseFile", "PrereqLicenseUrl"));
                                 }
@@ -181,31 +204,19 @@ namespace WixToolset.Bal
                                     prereqInfo.LicenseFile = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attribute);
                                 }
                                 break;
+                            }
                             case "PrereqLicenseUrl":
+                            {
+                                // at the time the extension attribute is parsed, the compiler might not yet have
+                                // parsed the PrereqPackage attribute, so we need to get it directly from the parent element.
+                                var prereqPackage = parentElement.Attribute(this.Namespace + "PrereqPackage");
+                                var prereqInfo = this.GetMbaPrereqInformationSymbol(section, sourceLineNumbers, prereqPackage, packageId);
 
-                                if (!this.prereqInfoSymbolsByPackageId.TryGetValue(packageId, out prereqInfo))
+                                if (prereqInfo == null)
                                 {
-                                    // at the time the extension attribute is parsed, the compiler might not yet have
-                                    // parsed the PrereqPackage attribute, so we need to get it directly from the parent element.
-                                    var prereqPackage = parentElement.Attribute(this.Namespace + "PrereqPackage");
-
-                                    if (null != prereqPackage && YesNoType.Yes == this.ParseHelper.GetAttributeYesNoValue(sourceLineNumbers, prereqPackage))
-                                    {
-                                        prereqInfo = section.AddSymbol(new WixMbaPrereqInformationSymbol(sourceLineNumbers)
-                                        {
-                                            PackageId = packageId,
-                                        });
-
-                                        this.prereqInfoSymbolsByPackageId.Add(packageId, prereqInfo);
-                                    }
-                                    else
-                                    {
-                                        this.Messaging.Write(BalErrors.AttributeRequiresPrereqPackage(sourceLineNumbers, parentElement.Name.LocalName, "PrereqLicenseUrl"));
-                                        break;
-                                    }
+                                    this.Messaging.Write(BalErrors.AttributeRequiresPrereqPackage(sourceLineNumbers, parentElement.Name.LocalName, "PrereqLicenseUrl"));
                                 }
-
-                                if (null != prereqInfo.LicenseFile)
+                                else if (null != prereqInfo.LicenseFile)
                                 {
                                     this.Messaging.Write(ErrorMessages.IllegalAttributeWithOtherAttribute(sourceLineNumbers, parentElement.Name.LocalName, "PrereqLicenseUrl", "PrereqLicenseFile"));
                                 }
@@ -214,19 +225,9 @@ namespace WixToolset.Bal
                                     prereqInfo.LicenseUrl = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attribute);
                                 }
                                 break;
+                            }
                             case "PrereqPackage":
-                                if (YesNoType.Yes == this.ParseHelper.GetAttributeYesNoValue(sourceLineNumbers, attribute))
-                                {
-                                    if (!this.prereqInfoSymbolsByPackageId.TryGetValue(packageId, out _))
-                                    {
-                                        prereqInfo = section.AddSymbol(new WixMbaPrereqInformationSymbol(sourceLineNumbers)
-                                        {
-                                            PackageId = packageId,
-                                        });
-
-                                        this.prereqInfoSymbolsByPackageId.Add(packageId, prereqInfo);
-                                    }
-                                }
+                                this.GetMbaPrereqInformationSymbol(section, sourceLineNumbers, attribute, packageId);
                                 break;
                             default:
                                 this.ParseHelper.UnexpectedAttribute(parentElement, attribute);
@@ -300,6 +301,41 @@ namespace WixToolset.Bal
             }
         }
 
+        private WixBalPackageInfoSymbol GetBalPackageInfoSymbol(IntermediateSection section, SourceLineNumber sourceLineNumbers, string packageId)
+        {
+            if (!this.packageInfoSymbolsByPackageId.TryGetValue(packageId, out var packageInfo))
+            {
+                packageInfo = section.AddSymbol(new WixBalPackageInfoSymbol(sourceLineNumbers, new Identifier(AccessModifier.Global, packageId))
+                {
+                    PackageId = packageId,
+                });
+
+                this.packageInfoSymbolsByPackageId.Add(packageId, packageInfo);
+            }
+
+            return packageInfo;
+        }
+
+        private WixMbaPrereqInformationSymbol GetMbaPrereqInformationSymbol(IntermediateSection section, SourceLineNumber sourceLineNumbers, XAttribute prereqAttribute, string packageId)
+        {
+            WixMbaPrereqInformationSymbol prereqInfo = null;
+
+            if (prereqAttribute != null && YesNoType.Yes == this.ParseHelper.GetAttributeYesNoValue(sourceLineNumbers, prereqAttribute))
+            {
+                if (!this.prereqInfoSymbolsByPackageId.TryGetValue(packageId, out _))
+                {
+                    prereqInfo = section.AddSymbol(new WixMbaPrereqInformationSymbol(sourceLineNumbers, new Identifier(AccessModifier.Global, packageId))
+                    {
+                        PackageId = packageId,
+                    });
+
+                    this.prereqInfoSymbolsByPackageId.Add(packageId, prereqInfo);
+                }
+            }
+
+            return prereqInfo;
+        }
+
         /// <summary>
         /// Parses a Condition element for Bundles.
         /// </summary>
@@ -418,6 +454,101 @@ namespace WixToolset.Bal
             }
         }
 
+        private void ParseWixInternalUIBootstrapperApplicationElement(Intermediate intermediate, IntermediateSection section, XElement node)
+        {
+            var sourceLineNumbers = this.ParseHelper.GetSourceLineNumbers(node);
+            WixInternalUIBootstrapperApplicationTheme? theme = null;
+            string themeFile = null;
+            string logoFile = null;
+            string localizationFile = null;
+
+            foreach (var attrib in node.Attributes())
+            {
+                if (String.IsNullOrEmpty(attrib.Name.NamespaceName) || this.Namespace == attrib.Name.Namespace)
+                {
+                    switch (attrib.Name.LocalName)
+                    {
+                        case "LogoFile":
+                            logoFile = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attrib);
+                            break;
+                        case "ThemeFile":
+                            themeFile = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attrib);
+                            break;
+                        case "LocalizationFile":
+                            localizationFile = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attrib);
+                            break;
+                        case "Theme":
+                            var themeValue = this.ParseHelper.GetAttributeValue(sourceLineNumbers, attrib);
+                            switch (themeValue)
+                            {
+                                case "none":
+                                    theme = WixInternalUIBootstrapperApplicationTheme.None;
+                                    break;
+                                case "standard":
+                                    theme = WixInternalUIBootstrapperApplicationTheme.Standard;
+                                    break;
+                                default:
+                                    this.Messaging.Write(ErrorMessages.IllegalAttributeValue(sourceLineNumbers, node.Name.LocalName, "Theme", themeValue, "none", "standard"));
+                                    theme = WixInternalUIBootstrapperApplicationTheme.Unknown;
+                                    break;
+                            }
+                            break;
+                        default:
+                            this.ParseHelper.UnexpectedAttribute(node, attrib);
+                            break;
+                    }
+                }
+                else
+                {
+                    this.ParseHelper.ParseExtensionAttribute(this.Context.Extensions, intermediate, section, node, attrib);
+                }
+            }
+
+            this.ParseHelper.ParseForExtensionElements(this.Context.Extensions, intermediate, section, node);
+
+            if (!theme.HasValue)
+            {
+                theme = WixInternalUIBootstrapperApplicationTheme.Standard;
+            }
+
+            if (!this.Messaging.EncounteredError)
+            {
+                if (!String.IsNullOrEmpty(logoFile))
+                {
+                    section.AddSymbol(new WixVariableSymbol(sourceLineNumbers, new Identifier(AccessModifier.Global, "WixIuibaLogo"))
+                    {
+                        Value = logoFile,
+                    });
+                }
+
+                if (!String.IsNullOrEmpty(themeFile))
+                {
+                    section.AddSymbol(new WixVariableSymbol(sourceLineNumbers, new Identifier(AccessModifier.Global, "WixIuibaThemeXml"))
+                    {
+                        Value = themeFile,
+                    });
+                }
+
+                if (!String.IsNullOrEmpty(localizationFile))
+                {
+                    section.AddSymbol(new WixVariableSymbol(sourceLineNumbers, new Identifier(AccessModifier.Global, "WixIuibaThemeWxl"))
+                    {
+                        Value = localizationFile,
+                    });
+                }
+
+                var baId = "WixInternalUIBootstrapperApplication";
+                switch (theme)
+                {
+                    case WixInternalUIBootstrapperApplicationTheme.Standard:
+                        baId = "WixInternalUIBootstrapperApplication.Standard";
+                        break;
+                }
+
+                this.CreateBARef(section, sourceLineNumbers, node, baId);
+            }
+        }
+
         /// <summary>
         /// Parses a WixStandardBootstrapperApplication element for Bundles.
         /// </summary>
diff --git a/src/ext/Bal/wixext/BalErrors.cs b/src/ext/Bal/wixext/BalErrors.cs
index e9f68b24..a7a00a4b 100644
--- a/src/ext/Bal/wixext/BalErrors.cs
+++ b/src/ext/Bal/wixext/BalErrors.cs
@@ -18,11 +18,41 @@ namespace WixToolset.Bal
             return Message(sourceLineNumbers, Ids.BAFunctionsPayloadRequiredInUXContainer, "The BAFunctions DLL Payload element must be located inside the BootstrapperApplication container.");
         }
 
+        public static Message IuibaNonMsiPrimaryPackage(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaNonMsiPrimaryPackage, "When using WixInternalUIBootstrapperApplication, each primary package must be an MsiPackage.");
+        }
+
+        public static Message IuibaNonPermanentNonPrimaryPackage(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaNonPermanentNonPrimaryPackage, "When using WixInternalUIBootstrapperApplication, packages must either be non-permanent and have the bal:PrimaryPackageType attribute, or be permanent and have the bal:PrereqPackage attribute set to 'yes'.");
+        }
+
+        public static Message IuibaNonPermanentPrereqPackage(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaNonPermanentPrereqPackage, "When using WixInternalUIBootstrapperApplication and bal:PrereqPackage is set to 'yes', the package must be permanent.");
+        }
+
+        public static Message IuibaPermanentPrimaryPackageType(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaPermanentPrimaryPackageType, "When using WixInternalUIBootstrapperApplication, packages with the bal:PrimaryPackageType attribute must not be permanent.");
+        }
+
+        public static Message IuibaPrimaryPackageEnableFeatureSelection(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaPrimaryPackageEnableFeatureSelection, "When using WixInternalUIBootstrapperApplication, primary packages must not have feature selection enabled because it interferes with the user selecting feature through the MSI UI.");
+        }
+
         public static Message MissingDNCPrereq()
         {
             return Message(null, Ids.MissingDNCPrereq, "There must be at least one PrereqPackage when using the DotNetCoreBootstrapperApplicationHost with SelfContainedDeployment set to \"no\".");
         }
 
+        public static Message MissingIUIPrimaryPackage()
+        {
+            return Message(null, Ids.MissingIUIPrimaryPackage, "When using WixInternalUIBootstrapperApplication, there must be one package with bal:PrimaryPackageType=\"default\".");
+        }
+
         public static Message MissingMBAPrereq()
         {
             return Message(null, Ids.MissingMBAPrereq, "There must be at least one PrereqPackage when using the ManagedBootstrapperApplicationHost.\nThis is typically done by using the WixNetFxExtension and referencing one of the NetFxAsPrereq package groups.");
@@ -38,6 +68,16 @@ namespace WixToolset.Bal
             return Message(sourceLineNumbers, Ids.MultiplePrereqLicenses, "There may only be one package in the bundle that has either the PrereqLicenseFile attribute or the PrereqLicenseUrl attribute.");
         }
 
+        public static Message MultiplePrimaryPackageType(SourceLineNumber sourceLineNumbers, string primaryPackageType)
+        {
+            return Message(sourceLineNumbers, Ids.MultiplePrimaryPackageType, "There may only be one package in the bundle with PrimaryPackageType of '{0}'.", primaryPackageType);
+        }
+
+        public static Message MultiplePrimaryPackageType2(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.MultiplePrimaryPackageType2, "The location of the package related to the previous error.");
+        }
+
         public static Message NonUpperCaseOverridableVariable(SourceLineNumber sourceLineNumbers, string name, string expectedName)
         {
             return Message(sourceLineNumbers, Ids.NonUpperCaseOverridableVariable, "Overridable variable '{0}' must be '{1}' with Bundle/@CommandLineVariables value 'upperCase'.", name, expectedName);
@@ -62,6 +102,14 @@ namespace WixToolset.Bal
             BAFunctionsPayloadRequiredInUXContainer = 6805,
             MissingDNCPrereq = 6806,
             NonUpperCaseOverridableVariable = 6807,
+            MissingIUIPrimaryPackage = 6808,
+            MultiplePrimaryPackageType = 6809,
+            MultiplePrimaryPackageType2 = 6810,
+            IuibaNonPermanentNonPrimaryPackage = 6811,
+            IuibaNonPermanentPrereqPackage = 6812,
+            IuibaPermanentPrimaryPackageType = 6813,
+            IuibaNonMsiPrimaryPackage = 6814,
+            IuibaPrimaryPackageEnableFeatureSelection = 6815,
         }
     }
 }
diff --git a/src/ext/Bal/wixext/BalWarnings.cs b/src/ext/Bal/wixext/BalWarnings.cs
index 18b25062..96e7a523 100644
--- a/src/ext/Bal/wixext/BalWarnings.cs
+++ b/src/ext/Bal/wixext/BalWarnings.cs
@@ -8,6 +8,26 @@ namespace WixToolset.Bal
 
     public static class BalWarnings
     {
+        public static Message IuibaForceCachePrereq(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaForceCachePrereq, "WixInternalUIBootstrapperApplication does not support the value of 'force' for Cache on prereq packages. Prereq packages are only cached when they need to be installed.");
+        }
+
+        public static Message IuibaPrereqPackageAfterPrimaryPackage(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaPrereqPackageAfterPrimaryPackage, "When using WixInternalUIBootstrapperApplication, all prereq packages should be before the primary package in the chain. The prereq packages are always installed before the primary package.");
+        }
+
+        public static Message IuibaPrimaryPackageDisplayInternalUICondition(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaPrimaryPackageDisplayInternalUICondition, "WixInternalUIBootstrapperApplication ignores DisplayInternalUICondition for the primary package so that the MSI UI is always shown.");
+        }
+
+        public static Message IuibaPrimaryPackageInstallCondition(SourceLineNumber sourceLineNumbers)
+        {
+            return Message(sourceLineNumbers, Ids.IuibaPrimaryPackageInstallCondition, "WixInternalUIBootstrapperApplication ignores InstallCondition for the primary package so that the MSI UI is always shown.");
+        }
+
         public static Message UnmarkedBAFunctionsDLL(SourceLineNumber sourceLineNumbers)
         {
             return Message(sourceLineNumbers, Ids.UnmarkedBAFunctionsDLL, "WixStandardBootstrapperApplication doesn't automatically load BAFunctions.dll. Use the bal:BAFunctions attribute to indicate that it should be loaded.");
@@ -26,6 +46,10 @@ namespace WixToolset.Bal
         public enum Ids
         {
             UnmarkedBAFunctionsDLL = 6501,
+            IuibaForceCachePrereq = 6502,
+            IuibaPrimaryPackageInstallCondition = 6503,
+            IuibaPrimaryPackageDisplayInternalUICondition = 6504,
+            IuibaPrereqPackageAfterPrimaryPackage = 6505,
         }
     }
 }
diff --git a/src/ext/Bal/wixext/Symbols/WixBalPackageInfoSymbol.cs b/src/ext/Bal/wixext/Symbols/WixBalPackageInfoSymbol.cs
index b09cb191..08d4ce4e 100644
--- a/src/ext/Bal/wixext/Symbols/WixBalPackageInfoSymbol.cs
+++ b/src/ext/Bal/wixext/Symbols/WixBalPackageInfoSymbol.cs
@@ -13,6 +13,7 @@ namespace WixToolset.Bal
             {
                 new IntermediateFieldDefinition(nameof(WixBalPackageInfoSymbolFields.PackageId), IntermediateFieldType.String),
                 new IntermediateFieldDefinition(nameof(WixBalPackageInfoSymbolFields.DisplayInternalUICondition), IntermediateFieldType.String),
+                new IntermediateFieldDefinition(nameof(WixBalPackageInfoSymbolFields.PrimaryPackageType), IntermediateFieldType.Number),
             },
             typeof(WixBalPackageInfoSymbol));
     }
@@ -26,6 +27,16 @@ namespace WixToolset.Bal.Symbols
     {
         PackageId,
         DisplayInternalUICondition,
+        PrimaryPackageType,
+    }
+
+    public enum BalPrimaryPackageType
+    {
+        None,
+        Default,
+        X86,
+        X64,
+        ARM64,
     }
 
     public class WixBalPackageInfoSymbol : IntermediateSymbol
@@ -51,5 +62,11 @@ namespace WixToolset.Bal.Symbols
             get => this.Fields[(int)WixBalPackageInfoSymbolFields.DisplayInternalUICondition].AsString();
             set => this.Set((int)WixBalPackageInfoSymbolFields.DisplayInternalUICondition, value);
         }
+
+        public BalPrimaryPackageType PrimaryPackageType
+        {
+            get => (BalPrimaryPackageType)this.Fields[(int)WixBalPackageInfoSymbolFields.PrimaryPackageType].AsNumber();
+            set => this.Set((int)WixBalPackageInfoSymbolFields.PrimaryPackageType, (int)value);
+        }
     }
 }
diff --git a/src/ext/Bal/wixiuiba/WixInternalUIBootstrapperApplication.cpp b/src/ext/Bal/wixiuiba/WixInternalUIBootstrapperApplication.cpp
new file mode 100644
index 00000000..dbb97366
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/WixInternalUIBootstrapperApplication.cpp
@@ -0,0 +1,918 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+#include "precomp.h"
+#include "BalBaseBootstrapperApplicationProc.h"
+#include "BalBaseBootstrapperApplication.h"
+
+static const LPCWSTR WIXIUIBA_WINDOW_CLASS = L"WixInternalUIBA";
+
+enum WM_WIXIUIBA
+{
+    WM_WIXIUIBA_DETECT_PACKAGES = WM_APP + 100,
+    WM_WIXIUIBA_PLAN_PACKAGES,
+    WM_WIXIUIBA_APPLY_PACKAGES,
+    WM_WIXIUIBA_DETECT_FOR_CLEANUP,
+    WM_WIXIUIBA_PLAN_PACKAGES_FOR_CLEANUP,
+};
+
+
+class CWixInternalUIBootstrapperApplication : public CBalBaseBootstrapperApplication
+{
+public: // IBootstrapperApplication
+    virtual STDMETHODIMP OnStartup()
+    {
+        HRESULT hr = S_OK;
+        DWORD dwUIThreadId = 0;
+
+        // create UI thread
+        m_hUiThread = ::CreateThread(NULL, 0, UiThreadProc, this, 0, &dwUIThreadId);
+        if (!m_hUiThread)
+        {
+            BalExitWithLastError(hr, "Failed to create UI thread.");
+        }
+
+    LExit:
+        return hr;
+    }
+
+
+    virtual STDMETHODIMP OnShutdown(
+        __inout BOOTSTRAPPER_SHUTDOWN_ACTION* pAction
+        )
+    {
+        // wait for UI thread to terminate
+        if (m_hUiThread)
+        {
+            ::WaitForSingleObject(m_hUiThread, INFINITE);
+            ReleaseHandle(m_hUiThread);
+        }
+
+        if (m_fFailedToLoadPackage)
+        {
+            Assert(FAILED(m_hrFinal));
+            m_pPrereqData->hrFatalError = m_hrFinal;
+            BalLog(BOOTSTRAPPER_LOG_LEVEL_ERROR, "Failed to load primary package as the BA. The bootstrapper application will be reloaded to show the error.");
+            *pAction = BOOTSTRAPPER_SHUTDOWN_ACTION_RELOAD_BOOTSTRAPPER;
+        }
+
+        return S_OK;
+    }
+
+
+    virtual STDMETHODIMP OnDetectPackageComplete(
+        __in_z LPCWSTR wzPackageId,
+        __in HRESULT hrStatus,
+        __in BOOTSTRAPPER_PACKAGE_STATE state,
+        __in BOOL fCached
+        )
+    {
+        BAL_INFO_PACKAGE* pPackage = NULL;
+
+        if (SUCCEEDED(hrStatus) && SUCCEEDED(BalInfoFindPackageById(&m_Bundle.packages, wzPackageId, &pPackage)) &&
+            BAL_INFO_PRIMARY_PACKAGE_TYPE_DEFAULT == pPackage->primaryPackageType)
+        {
+            BOOL fInstalled = BOOTSTRAPPER_PACKAGE_STATE_ABSENT < state;
+
+            // Maybe modify the action state if the primary package is or is not already installed.
+            if (fInstalled && BOOTSTRAPPER_ACTION_INSTALL == m_command.action)
+            {
+                m_command.action = BOOTSTRAPPER_ACTION_MODIFY;
+            }
+            else if (!fInstalled && (BOOTSTRAPPER_ACTION_MODIFY == m_command.action || BOOTSTRAPPER_ACTION_REPAIR == m_command.action))
+            {
+                m_command.action = BOOTSTRAPPER_ACTION_INSTALL;
+            }
+
+            if (m_fApplied && !fInstalled && fCached)
+            {
+                m_fAutomaticRemoval = TRUE;
+            }
+        }
+
+        return __super::OnDetectPackageComplete(wzPackageId, hrStatus, state, fCached);
+    }
+
+
+    virtual STDMETHODIMP OnDetectComplete(
+        __in HRESULT hrStatus,
+        __in BOOL fEligibleForCleanup
+        )
+    {
+        if (m_fAutomaticRemoval && SUCCEEDED(hrStatus))
+        {
+            ::PostMessageW(m_hWnd, WM_WIXIUIBA_PLAN_PACKAGES_FOR_CLEANUP, 0, BOOTSTRAPPER_ACTION_UNINSTALL);
+            ExitFunction();
+        }
+        else if (m_fApplied)
+        {
+            ::PostMessageW(m_hWnd, WM_CLOSE, 0, 0);
+            ExitFunction();
+        }
+
+        // If we're performing an action that modifies machine state then evaluate conditions.
+        BOOL fEvaluateConditions = SUCCEEDED(hrStatus) &&
+            (BOOTSTRAPPER_ACTION_LAYOUT < m_command.action && BOOTSTRAPPER_ACTION_UPDATE_REPLACE > m_command.action);
+
+        if (fEvaluateConditions)
+        {
+            hrStatus = EvaluateConditions();
+        }
+
+        if (SUCCEEDED(hrStatus))
+        {
+            ::PostMessageW(m_hWnd, WM_WIXIUIBA_PLAN_PACKAGES, 0, m_command.action);
+        }
+        else
+        {
+            SetLoadPackageFailure(hrStatus);
+        }
+
+    LExit:
+        return __super::OnDetectComplete(hrStatus, fEligibleForCleanup);
+    }
+
+
+    virtual STDMETHODIMP OnPlanPackageBegin(
+        __in_z LPCWSTR wzPackageId,
+        __in BOOTSTRAPPER_PACKAGE_STATE state,
+        __in BOOL fCached,
+        __in BOOTSTRAPPER_PACKAGE_CONDITION_RESULT installCondition,
+        __in BOOTSTRAPPER_PACKAGE_CONDITION_RESULT repairCondition,
+        __in BOOTSTRAPPER_REQUEST_STATE recommendedState,
+        __in BOOTSTRAPPER_CACHE_TYPE recommendedCacheType,
+        __inout BOOTSTRAPPER_REQUEST_STATE* pRequestState,
+        __inout BOOTSTRAPPER_CACHE_TYPE* pRequestedCacheType,
+        __inout BOOL* pfCancel
+        )
+    {
+        HRESULT hr = S_OK;
+        BAL_INFO_PACKAGE* pPackage = NULL;
+
+        hr = BalInfoFindPackageById(&m_Bundle.packages, wzPackageId, &pPackage);
+        if (FAILED(hr))
+        {
+            // Non-chain package, keep default.
+        }
+        else if (BAL_INFO_PRIMARY_PACKAGE_TYPE_DEFAULT != pPackage->primaryPackageType)
+        {
+            // Only the primary package should be cached or executed.
+            if (BOOTSTRAPPER_CACHE_TYPE_FORCE == *pRequestedCacheType)
+            {
+                *pRequestedCacheType = BOOTSTRAPPER_CACHE_TYPE_KEEP;
+            }
+
+            *pRequestState = BOOTSTRAPPER_REQUEST_STATE_NONE;
+        }
+        else if (BOOTSTRAPPER_DISPLAY_FULL == m_command.display && !m_fAutomaticRemoval)
+        {
+            // Make sure the MSI UI is shown regardless of the current state of the package.
+            *pRequestState = BOOTSTRAPPER_REQUEST_STATE_REPAIR;
+        }
+
+        return __super::OnPlanPackageBegin(wzPackageId, state, fCached, installCondition, repairCondition, recommendedState, recommendedCacheType, pRequestState, pRequestedCacheType, pfCancel);
+    }
+
+
+    virtual STDMETHODIMP OnPlanMsiPackage(
+        __in_z LPCWSTR wzPackageId,
+        __in BOOL fExecute,
+        __in BOOTSTRAPPER_ACTION_STATE action,
+        __in BOOTSTRAPPER_MSI_FILE_VERSIONING recommendedFileVersioning,
+        __inout BOOL* pfCancel,
+        __inout BURN_MSI_PROPERTY* pActionMsiProperty,
+        __inout INSTALLUILEVEL* pUiLevel,
+        __inout BOOL* pfDisableExternalUiHandler,
+        __inout BOOTSTRAPPER_MSI_FILE_VERSIONING* pFileVersioning
+        )
+    {
+        INSTALLUILEVEL uiLevel = INSTALLUILEVEL_NOCHANGE;
+
+        if (m_fAutomaticRemoval)
+        {
+            ExitFunction();
+        }
+
+        switch (m_command.display)
+        {
+        case BOOTSTRAPPER_DISPLAY_FULL:
+            uiLevel = INSTALLUILEVEL_FULL;
+            break;
+
+        case BOOTSTRAPPER_DISPLAY_PASSIVE:
+            uiLevel = INSTALLUILEVEL_REDUCED;
+            break;
+        }
+
+        if (INSTALLUILEVEL_NOCHANGE != uiLevel)
+        {
+            *pUiLevel = uiLevel;
+        }
+
+        *pActionMsiProperty = BURN_MSI_PROPERTY_NONE;
+        *pfDisableExternalUiHandler = TRUE;
+
+    LExit:
+        return __super::OnPlanMsiPackage(wzPackageId, fExecute, action, recommendedFileVersioning, pfCancel, pActionMsiProperty, pUiLevel, pfDisableExternalUiHandler, pFileVersioning);
+    }
+
+
+    virtual STDMETHODIMP OnPlanComplete(
+        __in HRESULT hrStatus
+        )
+    {
+        if (SUCCEEDED(hrStatus))
+        {
+            ::PostMessageW(m_hWnd, WM_WIXIUIBA_APPLY_PACKAGES, 0, 0);
+        }
+        else if (m_fAutomaticRemoval)
+        {
+            ::PostMessageW(m_hWnd, WM_CLOSE, 0, 0);
+        }
+        else
+        {
+            SetLoadPackageFailure(hrStatus);
+        }
+
+        return __super::OnPlanComplete(hrStatus);
+    }
+
+
+    virtual STDMETHODIMP OnApplyBegin(
+        __in DWORD dwPhaseCount,
+        __inout BOOL* pfCancel
+        )
+    {
+        m_fApplying = TRUE;
+        return __super::OnApplyBegin(dwPhaseCount, pfCancel);
+    }
+
+
+    virtual STDMETHODIMP OnCacheComplete(
+        __in HRESULT hrStatus
+        )
+    {
+        if (FAILED(hrStatus) && !m_fAutomaticRemoval)
+        {
+            SetLoadPackageFailure(hrStatus);
+        }
+
+        return __super::OnCacheComplete(hrStatus);
+    }
+
+
+    virtual STDMETHODIMP OnExecuteBegin(
+        __in DWORD cExecutingPackages,
+        __in BOOL* pfCancel
+        )
+    {
+        m_pEngine->CloseSplashScreen();
+
+        return __super::OnExecuteBegin(cExecutingPackages, pfCancel);
+    }
+
+
+    virtual STDMETHODIMP OnApplyComplete(
+        __in HRESULT hrStatus,
+        __in BOOTSTRAPPER_APPLY_RESTART restart,
+        __in BOOTSTRAPPER_APPLYCOMPLETE_ACTION recommendation,
+        __inout BOOTSTRAPPER_APPLYCOMPLETE_ACTION* pAction
+        )
+    {
+        HRESULT hr = __super::OnApplyComplete(hrStatus, restart, recommendation, pAction);
+
+        *pAction = BOOTSTRAPPER_APPLYCOMPLETE_ACTION_NONE;
+        m_fApplying = FALSE;
+
+        if (m_fAutomaticRemoval)
+        {
+            ::PostMessageW(m_hWnd, WM_CLOSE, 0, 0);
+        }
+        else
+        {
+            m_restartResult = restart; // remember the restart result so we return the correct error code.
+            m_fApplied = TRUE;
+
+            if (FAILED(hrStatus))
+            {
+                m_hrFinal = hrStatus;
+            }
+
+            ::PostMessageW(m_hWnd, WM_WIXIUIBA_DETECT_FOR_CLEANUP, 0, 0);
+        }
+
+        return hr;
+    }
+
+
+public: //CBalBaseBootstrapperApplication
+    virtual STDMETHODIMP Initialize(
+        __in const BOOTSTRAPPER_CREATE_ARGS* pCreateArgs
+        )
+    {
+        HRESULT hr = S_OK;
+
+        hr = __super::Initialize(pCreateArgs);
+        BalExitOnFailure(hr, "CBalBaseBootstrapperApplication initialization failed.");
+
+        memcpy_s(&m_command, sizeof(m_command), pCreateArgs->pCommand, sizeof(BOOTSTRAPPER_COMMAND));
+        memcpy_s(&m_createArgs, sizeof(m_createArgs), pCreateArgs, sizeof(BOOTSTRAPPER_CREATE_ARGS));
+        m_createArgs.pCommand = &m_command;
+
+    LExit:
+        return hr;
+    }
+
+    void Uninitialize(
+        __in const BOOTSTRAPPER_DESTROY_ARGS* /*pArgs*/,
+        __in BOOTSTRAPPER_DESTROY_RESULTS* /*pResults*/
+        )
+    {
+    }
+
+
+private:
+    //
+    // UiThreadProc - entrypoint for UI thread.
+    //
+    static DWORD WINAPI UiThreadProc(
+        __in LPVOID pvContext
+        )
+    {
+        HRESULT hr = S_OK;
+        CWixInternalUIBootstrapperApplication* pThis = (CWixInternalUIBootstrapperApplication*)pvContext;
+        BOOL fComInitialized = FALSE;
+        BOOL fRet = FALSE;
+        MSG msg = { };
+        DWORD dwQuit = 0;
+
+        // Initialize COM and theme.
+        hr = ::CoInitialize(NULL);
+        BalExitOnFailure(hr, "Failed to initialize COM.");
+        fComInitialized = TRUE;
+
+        hr = pThis->InitializeData();
+        BalExitOnFailure(hr, "Failed to initialize data in bootstrapper application.");
+
+        // Create main window.
+        hr = pThis->CreateMainWindow();
+        BalExitOnFailure(hr, "Failed to create main window.");
+
+        ::PostMessageW(pThis->m_hWnd, WM_WIXIUIBA_DETECT_PACKAGES, 0, 0);
+
+        // message pump
+        while (0 != (fRet = ::GetMessageW(&msg, NULL, 0, 0)))
+        {
+            if (-1 == fRet)
+            {
+                hr = E_UNEXPECTED;
+                BalExitOnFailure(hr, "Unexpected return value from message pump.");
+            }
+            else if (!::IsDialogMessageW(pThis->m_hWnd, &msg))
+            {
+                ::TranslateMessage(&msg);
+                ::DispatchMessageW(&msg);
+            }
+        }
+
+        // Succeeded thus far, check to see if anything went wrong while actually
+        // executing changes.
+        if (FAILED(pThis->m_hrFinal))
+        {
+            hr = pThis->m_hrFinal;
+        }
+        else if (pThis->CheckCanceled())
+        {
+            hr = HRESULT_FROM_WIN32(ERROR_INSTALL_USEREXIT);
+        }
+
+    LExit:
+        // destroy main window
+        pThis->DestroyMainWindow();
+
+        if (BOOTSTRAPPER_APPLY_RESTART_INITIATED == pThis->m_restartResult)
+        {
+            dwQuit = ERROR_SUCCESS_REBOOT_INITIATED;
+        }
+        else if (BOOTSTRAPPER_APPLY_RESTART_REQUIRED == pThis->m_restartResult)
+        {
+            dwQuit = ERROR_SUCCESS_REBOOT_REQUIRED;
+        }
+        else if (SEVERITY_ERROR == HRESULT_SEVERITY(hr) && FACILITY_WIN32 == HRESULT_FACILITY(hr))
+        {
+            // Convert Win32 HRESULTs back to the error code.
+            dwQuit = HRESULT_CODE(hr);
+        }
+        else
+        {
+            dwQuit = hr;
+        }
+
+        // initiate engine shutdown
+        pThis->m_pEngine->Quit(dwQuit);
+
+        // uninitialize COM
+        if (fComInitialized)
+        {
+            ::CoUninitialize();
+        }
+
+        return hr;
+    }
+
+
+    //
+    // InitializeData - initializes all the package and prerequisite information.
+    //
+    HRESULT InitializeData()
+    {
+        HRESULT hr = S_OK;
+        IXMLDOMDocument* pixdManifest = NULL;
+
+        hr = BalManifestLoad(m_hModule, &pixdManifest);
+        BalExitOnFailure(hr, "Failed to load bootstrapper application manifest.");
+
+        hr = BalInfoParseFromXml(&m_Bundle, pixdManifest);
+        BalExitOnFailure(hr, "Failed to load bundle information.");
+
+        hr = EnsureSinglePrimaryPackage();
+        BalExitOnFailure(hr, "Failed to ensure single primary package.");
+
+        hr = ProcessCommandLine();
+        ExitOnFailure(hr, "Unknown commandline parameters.");
+
+        hr = BalConditionsParseFromXml(&m_Conditions, pixdManifest, NULL);
+        BalExitOnFailure(hr, "Failed to load conditions from XML.");
+
+    LExit:
+        ReleaseObject(pixdManifest);
+
+        return hr;
+    }
+
+
+    //
+    // ProcessCommandLine - process the provided command line arguments.
+    //
+    HRESULT ProcessCommandLine()
+    {
+        HRESULT hr = S_OK;
+        int argc = 0;
+        LPWSTR* argv = NULL;
+
+        argc = m_BalInfoCommand.cUnknownArgs;
+        argv = m_BalInfoCommand.rgUnknownArgs;
+
+        for (int i = 0; i < argc; ++i)
+        {
+            BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "Ignoring unknown argument: %ls", argv[i]);
+        }
+
+        hr = BalSetOverridableVariablesFromEngine(&m_Bundle.overridableVariables, &m_BalInfoCommand, m_pEngine);
+        BalExitOnFailure(hr, "Failed to set overridable variables from the command line.");
+
+    LExit:
+        return hr;
+    }
+
+    HRESULT EnsureSinglePrimaryPackage()
+    {
+        HRESULT hr = S_OK;
+        BAL_INFO_PACKAGE* pDefaultPackage = NULL;
+        BOOL fPrimaryArchSpecific = FALSE;
+        USHORT usNativeMachine = 0;
+        BAL_INFO_PRIMARY_PACKAGE_TYPE nativeType = BAL_INFO_PRIMARY_PACKAGE_TYPE_NONE;
+
+        hr = ProcNativeMachine(::GetCurrentProcess(), &usNativeMachine);
+        BalExitOnFailure(hr, "Failed to get native machine value.");
+
+        if (S_FALSE != hr)
+        {
+            switch (usNativeMachine)
+            {
+            case IMAGE_FILE_MACHINE_I386:
+                nativeType = BAL_INFO_PRIMARY_PACKAGE_TYPE_X86;
+                break;
+            case IMAGE_FILE_MACHINE_AMD64:
+                nativeType = BAL_INFO_PRIMARY_PACKAGE_TYPE_X64;
+                break;
+            case IMAGE_FILE_MACHINE_ARM64:
+                nativeType = BAL_INFO_PRIMARY_PACKAGE_TYPE_ARM64;
+                break;
+            }
+        }
+        else
+        {
+#if !defined(_WIN64)
+            BOOL fIsWow64 = FALSE;
+
+            ProcWow64(::GetCurrentProcess(), &fIsWow64);
+            if (!fIsWow64)
+            {
+                nativeType = BAL_INFO_PRIMARY_PACKAGE_TYPE_X86;
+            }
+            else
+#endif
+            {
+                nativeType = BAL_INFO_PRIMARY_PACKAGE_TYPE_X64;
+            }
+        }
+
+        for (DWORD i = 0; i < m_Bundle.packages.cPackages; ++i)
+        {
+            BAL_INFO_PACKAGE* pPackage = m_Bundle.packages.rgPackages + i;
+
+            if (BAL_INFO_PRIMARY_PACKAGE_TYPE_NONE == pPackage->primaryPackageType)
+            {
+                // Skip.
+            }
+            else if (nativeType == pPackage->primaryPackageType)
+            {
+                if (fPrimaryArchSpecific)
+                {
+                    BalExitWithRootFailure(hr, E_INVALIDDATA, "Bundle contains multiple primary packages for same architecture: %u.", nativeType);
+                }
+
+                pPackage->primaryPackageType = BAL_INFO_PRIMARY_PACKAGE_TYPE_DEFAULT;
+                fPrimaryArchSpecific = TRUE;
+            }
+            else if (BAL_INFO_PRIMARY_PACKAGE_TYPE_DEFAULT == pPackage->primaryPackageType)
+            {
+                if (pDefaultPackage)
+                {
+                    BalExitWithRootFailure(hr, E_INVALIDDATA, "Bundle contains multiple default primary packages.");
+                }
+
+                pDefaultPackage = pPackage;
+            }
+        }
+
+        BalExitOnNull(pDefaultPackage, hr, E_INVALIDSTATE, "Bundle did not contain default primary package.");
+
+        if (fPrimaryArchSpecific)
+        {
+            pDefaultPackage->primaryPackageType = BAL_INFO_PRIMARY_PACKAGE_TYPE_NONE;
+        }
+
+    LExit:
+        return hr;
+    }
+
+
+    //
+    // CreateMainWindow - creates the main install window.
+    //
+    HRESULT CreateMainWindow()
+    {
+        HRESULT hr = S_OK;
+        WNDCLASSW wc = { };
+        DWORD dwWindowStyle = WS_POPUP;
+
+        wc.lpfnWndProc = CWixInternalUIBootstrapperApplication::WndProc;
+        wc.hInstance = m_hModule;
+        wc.lpszClassName = WIXIUIBA_WINDOW_CLASS;
+
+        if (!::RegisterClassW(&wc))
+        {
+            ExitWithLastError(hr, "Failed to register window.");
+        }
+
+        m_fRegistered = TRUE;
+
+        // If the UI should be visible, allow it to be visible and activated so we are the foreground window.
+        // This allows the UAC prompt and MSI UI to automatically be activated.
+        if (BOOTSTRAPPER_DISPLAY_NONE < m_command.display)
+        {
+            dwWindowStyle |= WS_VISIBLE;
+        }
+
+        m_hWnd = ::CreateWindowExW(WS_EX_TOOLWINDOW, wc.lpszClassName, NULL, dwWindowStyle, 0, 0, 0, 0, HWND_DESKTOP, NULL, m_hModule, this);
+        ExitOnNullWithLastError(m_hWnd, hr, "Failed to create window.");
+
+    LExit:
+        return hr;
+    }
+
+    //
+    // DestroyMainWindow - clean up all the window registration.
+    //
+    void DestroyMainWindow()
+    {
+        if (::IsWindow(m_hWnd))
+        {
+            ::DestroyWindow(m_hWnd);
+            m_hWnd = NULL;
+        }
+
+        if (m_fRegistered)
+        {
+            ::UnregisterClassW(WIXIUIBA_WINDOW_CLASS, m_hModule);
+            m_fRegistered = FALSE;
+        }
+    }
+
+    //
+    // WndProc - standard windows message handler.
+    //
+    static LRESULT CALLBACK WndProc(
+        __in HWND hWnd,
+        __in UINT uMsg,
+        __in WPARAM wParam,
+        __in LPARAM lParam
+        )
+    {
+#pragma warning(suppress:4312)
+        CWixInternalUIBootstrapperApplication* pBA = reinterpret_cast<CWixInternalUIBootstrapperApplication*>(::GetWindowLongPtrW(hWnd, GWLP_USERDATA));
+
+        switch (uMsg)
+        {
+        case WM_NCCREATE:
+        {
+            LPCREATESTRUCT lpcs = reinterpret_cast<LPCREATESTRUCT>(lParam);
+            pBA = reinterpret_cast<CWixInternalUIBootstrapperApplication*>(lpcs->lpCreateParams);
+#pragma warning(suppress:4244)
+            ::SetWindowLongPtrW(hWnd, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(pBA));
+        }
+        break;
+
+        case WM_NCDESTROY:
+        {
+            LRESULT lres = ::DefWindowProcW(hWnd, uMsg, wParam, lParam);
+            ::SetWindowLongPtrW(hWnd, GWLP_USERDATA, 0);
+            ::PostQuitMessage(0);
+            return lres;
+        }
+
+        case WM_CLOSE:
+            // If the user chose not to close, do *not* let the default window proc handle the message.
+            if (!pBA->OnClose())
+            {
+                return 0;
+            }
+            break;
+
+        case WM_WIXIUIBA_DETECT_PACKAGES: __fallthrough;
+        case WM_WIXIUIBA_DETECT_FOR_CLEANUP:
+            pBA->OnDetect();
+            return 0;
+
+        case WM_WIXIUIBA_PLAN_PACKAGES:
+        case WM_WIXIUIBA_PLAN_PACKAGES_FOR_CLEANUP:
+            pBA->OnPlan(static_cast<BOOTSTRAPPER_ACTION>(lParam));
+            return 0;
+
+        case WM_WIXIUIBA_APPLY_PACKAGES:
+            pBA->OnApply();
+            return 0;
+        }
+
+        return ::DefWindowProcW(hWnd, uMsg, wParam, lParam);
+    }
+
+
+    //
+    // OnDetect - start the processing of packages.
+    //
+    void OnDetect()
+    {
+        HRESULT hr = S_OK;
+
+        hr = m_pEngine->Detect();
+        BalExitOnFailure(hr, "Failed to start detecting chain.");
+
+    LExit:
+        if (FAILED(hr))
+        {
+            SetLoadPackageFailure(hr);
+        }
+    }
+
+
+    //
+    // OnPlan - plan the detected changes.
+    //
+    void OnPlan(
+        __in BOOTSTRAPPER_ACTION action
+        )
+    {
+        HRESULT hr = S_OK;
+
+        m_plannedAction = action;
+
+        hr = m_pEngine->Plan(action);
+        BalExitOnFailure(hr, "Failed to start planning packages.");
+
+    LExit:
+        if (FAILED(hr))
+        {
+            SetLoadPackageFailure(hr);
+        }
+    }
+
+
+    //
+    // OnApply - apply the packages.
+    //
+    void OnApply()
+    {
+        HRESULT hr = S_OK;
+
+        hr = m_pEngine->Apply(m_hWnd);
+        BalExitOnFailure(hr, "Failed to start applying packages.");
+
+    LExit:
+        if (FAILED(hr))
+        {
+            SetLoadPackageFailure(hr);
+        }
+    }
+
+
+    //
+    // OnClose - called when the window is trying to be closed.
+    //
+    BOOL OnClose()
+    {
+        BOOL fClose = FALSE;
+
+        // If we've already applied, just close.
+        if (m_fApplied)
+        {
+            fClose = TRUE;
+        }
+        else
+        {
+            PromptCancel(m_hWnd, TRUE, NULL, NULL);
+
+            // If we're inside Apply then we never close, we just cancel to let rollback occur.
+            fClose = !m_fApplying;
+        }
+
+        return fClose;
+    }
+
+
+    HRESULT EvaluateConditions()
+    {
+        HRESULT hr = S_OK;
+        BOOL fResult = FALSE;
+
+        for (DWORD i = 0; i < m_Conditions.cConditions; ++i)
+        {
+            BAL_CONDITION* pCondition = m_Conditions.rgConditions + i;
+
+            hr = BalConditionEvaluate(pCondition, m_pEngine, &fResult, &m_sczFailedMessage);
+            BalExitOnFailure(hr, "Failed to evaluate condition.");
+
+            if (!fResult)
+            {
+                hr = E_WIXSTDBA_CONDITION_FAILED;
+                BalExitOnFailure(hr, "%ls", m_sczFailedMessage);
+            }
+        }
+
+        ReleaseNullStrSecure(m_sczFailedMessage);
+
+    LExit:
+        return hr;
+    }
+
+
+    void SetLoadPackageFailure(
+        __in HRESULT hrStatus
+        )
+    {
+        Assert(FAILED(hrStatus));
+
+        if (!m_fApplied)
+        {
+            m_hrFinal = hrStatus;
+            m_fFailedToLoadPackage = TRUE;
+        }
+
+        // Quietly exit.
+        ::PostMessageW(m_hWnd, WM_CLOSE, 0, 0);
+    }
+
+
+public:
+    //
+    // Constructor - initialize member variables.
+    //
+    CWixInternalUIBootstrapperApplication(
+        __in HMODULE hModule,
+        __in_opt PREQBA_DATA* pPrereqData,
+        __in IBootstrapperEngine* pEngine
+        ) : CBalBaseBootstrapperApplication(pEngine, 3, 3000)
+    {
+        m_hModule = hModule;
+        m_command = { };
+        m_createArgs = { };
+
+        m_plannedAction = BOOTSTRAPPER_ACTION_UNKNOWN;
+
+        m_Bundle = { };
+        m_Conditions = { };
+        m_sczConfirmCloseMessage = NULL;
+        m_sczFailedMessage = NULL;
+
+        m_hUiThread = NULL;
+        m_fRegistered = FALSE;
+        m_hWnd = NULL;
+
+        m_hrFinal = S_OK;
+
+        m_restartResult = BOOTSTRAPPER_APPLY_RESTART_NONE;
+
+        m_fApplying = FALSE;
+        m_fApplied = FALSE;
+        m_fAutomaticRemoval = FALSE;
+        m_fFailedToLoadPackage = FALSE;
+        m_pPrereqData = pPrereqData;
+
+        pEngine->AddRef();
+        m_pEngine = pEngine;
+    }
+
+
+    //
+    // Destructor - release member variables.
+    //
+    ~CWixInternalUIBootstrapperApplication()
+    {
+        ReleaseStr(m_sczFailedMessage);
+        ReleaseStr(m_sczConfirmCloseMessage);
+        BalConditionsUninitialize(&m_Conditions);
+        BalInfoUninitialize(&m_Bundle);
+
+        ReleaseNullObject(m_pEngine);
+    }
+
+private:
+    HMODULE m_hModule;
+    BOOTSTRAPPER_CREATE_ARGS m_createArgs;
+    BOOTSTRAPPER_COMMAND m_command;
+    IBootstrapperEngine* m_pEngine;
+    BOOTSTRAPPER_ACTION m_plannedAction;
+
+    BAL_INFO_BUNDLE m_Bundle;
+    BAL_CONDITIONS m_Conditions;
+    LPWSTR m_sczFailedMessage;
+    LPWSTR m_sczConfirmCloseMessage;
+
+    HANDLE m_hUiThread;
+    BOOL m_fRegistered;
+    HWND m_hWnd;
+
+    HRESULT m_hrFinal;
+
+    BOOTSTRAPPER_APPLY_RESTART m_restartResult;
+
+    BOOL m_fApplying;
+    BOOL m_fApplied;
+    BOOL m_fAutomaticRemoval;
+    BOOL m_fFailedToLoadPackage;
+    PREQBA_DATA* m_pPrereqData;
+};
+
+
+//
+// CreateBootstrapperApplication - creates a new IBootstrapperApplication object.
+//
+HRESULT CreateBootstrapperApplication(
+    __in HMODULE hModule,
+    __in_opt PREQBA_DATA* pPrereqData,
+    __in IBootstrapperEngine* pEngine,
+    __in const BOOTSTRAPPER_CREATE_ARGS* pArgs,
+    __inout BOOTSTRAPPER_CREATE_RESULTS* pResults,
+    __out IBootstrapperApplication** ppApplication
+    )
+{
+    HRESULT hr = S_OK;
+    CWixInternalUIBootstrapperApplication* pApplication = NULL;
+
+    pApplication = new CWixInternalUIBootstrapperApplication(hModule, pPrereqData, pEngine);
+    BalExitOnNull(pApplication, hr, E_OUTOFMEMORY, "Failed to create new InternalUI bootstrapper application object.");
+
+    hr = pApplication->Initialize(pArgs);
+    ExitOnFailure(hr, "CWixInternalUIBootstrapperApplication initialization failed.");
+
+    pResults->pfnBootstrapperApplicationProc = BalBaseBootstrapperApplicationProc;
+    pResults->pvBootstrapperApplicationProcContext = pApplication;
+    *ppApplication = pApplication;
+    pApplication = NULL;
+
+LExit:
+    ReleaseObject(pApplication);
+    return hr;
+}
+
+
+void DestroyBootstrapperApplication(
+    __in IBootstrapperApplication* pApplication,
+    __in const BOOTSTRAPPER_DESTROY_ARGS* pArgs,
+    __inout BOOTSTRAPPER_DESTROY_RESULTS* pResults
+    )
+{
+    CWixInternalUIBootstrapperApplication* pBA = (CWixInternalUIBootstrapperApplication*)pApplication;
+    pBA->Uninitialize(pArgs, pResults);
+}
diff --git a/src/ext/Bal/wixiuiba/WixInternalUIBootstrapperApplication.h b/src/ext/Bal/wixiuiba/WixInternalUIBootstrapperApplication.h
new file mode 100644
index 00000000..b0b782dd
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/WixInternalUIBootstrapperApplication.h
@@ -0,0 +1,18 @@
+#pragma once
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+
+HRESULT CreateBootstrapperApplication(
+    __in HMODULE hModule,
+    __in_opt PREQBA_DATA* pPrereqData,
+    __in IBootstrapperEngine* pEngine,
+    __in const BOOTSTRAPPER_CREATE_ARGS* pArgs,
+    __inout BOOTSTRAPPER_CREATE_RESULTS* pResults,
+    __out IBootstrapperApplication** ppApplication
+    );
+
+void DestroyBootstrapperApplication(
+    __in IBootstrapperApplication* pApplication,
+    __in const BOOTSTRAPPER_DESTROY_ARGS* pArgs,
+    __inout BOOTSTRAPPER_DESTROY_RESULTS* pResults
+    );
diff --git a/src/ext/Bal/wixiuiba/precomp.cpp b/src/ext/Bal/wixiuiba/precomp.cpp
new file mode 100644
index 00000000..37664a1c
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/precomp.cpp
@@ -0,0 +1,3 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+#include "precomp.h"
diff --git a/src/ext/Bal/wixiuiba/precomp.h b/src/ext/Bal/wixiuiba/precomp.h
new file mode 100644
index 00000000..89ec6eab
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/precomp.h
@@ -0,0 +1,30 @@
+#pragma once
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+
+#include <windows.h>
+#include <msiquery.h>
+
+#include <dutil.h>
+#include <dictutil.h>
+#include <locutil.h>
+#include <osutil.h>
+#include <pathutil.h>
+#include <procutil.h>
+#include <regutil.h>
+#include <strutil.h>
+#include <xmlutil.h>
+
+#include <BootstrapperEngine.h>
+#include <BootstrapperApplication.h>
+#include <IBootstrapperEngine.h>
+#include <IBootstrapperApplication.h>
+
+#include <balutil.h>
+#include <balinfo.h>
+#include <balcondition.h>
+
+#include <preqba.h>
+
+#include "WixInternalUIBootstrapperApplication.h"
+#include "wixiuiba.h"
diff --git a/src/ext/Bal/wixiuiba/wixiuiba.cpp b/src/ext/Bal/wixiuiba/wixiuiba.cpp
new file mode 100644
index 00000000..3e751893
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/wixiuiba.cpp
@@ -0,0 +1,192 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+#include "precomp.h"
+
+static INTERNAL_UI_BA_STATE vstate = { };
+
+
+// internal function declarations
+
+static HRESULT LoadModulePaths(
+    __in INTERNAL_UI_BA_STATE* pState
+    );
+static HRESULT LoadInternalUIBAConfiguration(
+    __in INTERNAL_UI_BA_STATE* pState,
+    __in const BOOTSTRAPPER_CREATE_ARGS* pArgs
+    );
+static HRESULT CreatePrerequisiteBA(
+    __in INTERNAL_UI_BA_STATE* pState,
+    __in IBootstrapperEngine* pEngine,
+    __in const BOOTSTRAPPER_CREATE_ARGS* pArgs,
+    __inout BOOTSTRAPPER_CREATE_RESULTS* pResults
+    );
+
+
+// function definitions
+
+extern "C" BOOL WINAPI DllMain(
+    __in HINSTANCE hInstance,
+    __in DWORD dwReason,
+    __in LPVOID /*pvReserved*/
+    )
+{
+    switch (dwReason)
+    {
+    case DLL_PROCESS_ATTACH:
+        ::DisableThreadLibraryCalls(hInstance);
+        vstate.hInstance = hInstance;
+        break;
+
+    case DLL_PROCESS_DETACH:
+        vstate.hInstance = NULL;
+        break;
+    }
+
+    return TRUE;
+}
+
+// Note: This function assumes that COM was already initialized on the thread.
+extern "C" HRESULT WINAPI BootstrapperApplicationCreate(
+    __in const BOOTSTRAPPER_CREATE_ARGS* pArgs,
+    __inout BOOTSTRAPPER_CREATE_RESULTS* pResults
+    )
+{
+    HRESULT hr = S_OK; 
+    IBootstrapperEngine* pEngine = NULL;
+
+    hr = BalInitializeFromCreateArgs(pArgs, &pEngine);
+    ExitOnFailure(hr, "Failed to initialize Bal.");
+
+    if (!vstate.fInitialized)
+    {
+        hr = XmlInitialize();
+        BalExitOnFailure(hr, "Failed to initialize XML.");
+
+        hr = LoadModulePaths(&vstate);
+        BalExitOnFailure(hr, "Failed to load the module paths.");
+
+        hr = LoadInternalUIBAConfiguration(&vstate, pArgs);
+        BalExitOnFailure(hr, "Failed to get the InternalUIBA configuration.");
+
+        vstate.fInitialized = TRUE;
+    }
+
+    if (vstate.prereqData.fAlwaysInstallPrereqs && !vstate.prereqData.fCompleted ||
+        FAILED(vstate.prereqData.hrFatalError))
+    {
+        BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "Loading prerequisite bootstrapper application.");
+
+        hr = CreatePrerequisiteBA(&vstate, pEngine, pArgs, pResults);
+        BalExitOnFailure(hr, "Failed to create the pre-requisite bootstrapper application.");
+    }
+    else
+    {
+        hr = CreateBootstrapperApplication(vstate.hInstance, &vstate.prereqData, pEngine, pArgs, pResults, &vstate.pApplication);
+        BalExitOnFailure(hr, "Failed to create bootstrapper application interface.");
+    }
+
+LExit:
+    ReleaseNullObject(pEngine);
+
+    return hr;
+}
+
+extern "C" void WINAPI BootstrapperApplicationDestroy(
+    __in const BOOTSTRAPPER_DESTROY_ARGS* pArgs,
+    __in BOOTSTRAPPER_DESTROY_RESULTS* pResults
+    )
+{
+    BOOTSTRAPPER_DESTROY_RESULTS childResults = { };
+
+    if (vstate.hPrereqModule)
+    {
+        PFN_BOOTSTRAPPER_APPLICATION_DESTROY pfnDestroy = reinterpret_cast<PFN_BOOTSTRAPPER_APPLICATION_DESTROY>(::GetProcAddress(vstate.hPrereqModule, "PrereqBootstrapperApplicationDestroy"));
+        if (pfnDestroy)
+        {
+            (*pfnDestroy)(pArgs, &childResults);
+        }
+
+        ::FreeLibrary(vstate.hPrereqModule);
+        vstate.hPrereqModule = NULL;
+    }
+
+    if (vstate.pApplication)
+    {
+        DestroyBootstrapperApplication(vstate.pApplication, pArgs, pResults);
+        ReleaseNullObject(vstate.pApplication);
+    }
+
+    BalUninitialize();
+
+    // Need to keep track of state between reloads.
+    pResults->fDisableUnloading = TRUE;
+}
+
+static HRESULT LoadModulePaths(
+    __in INTERNAL_UI_BA_STATE* pState
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczFullPath = NULL;
+
+    hr = PathForCurrentProcess(&sczFullPath, pState->hInstance);
+    ExitOnFailure(hr, "Failed to get the full host path.");
+
+    hr = PathGetDirectory(sczFullPath, &pState->sczAppBase);
+    ExitOnFailure(hr, "Failed to get the directory of the full process path.");
+
+LExit:
+    ReleaseStr(sczFullPath);
+
+    return hr;
+}
+
+static HRESULT LoadInternalUIBAConfiguration(
+    __in INTERNAL_UI_BA_STATE* pState,
+    __in const BOOTSTRAPPER_CREATE_ARGS* /*pArgs*/
+    )
+{
+    HRESULT hr = S_OK;
+
+    pState->prereqData.fAlwaysInstallPrereqs = TRUE;
+    pState->prereqData.fPerformHelp = TRUE;
+    pState->prereqData.fPerformLayout = TRUE;
+
+    return hr;
+}
+
+static HRESULT CreatePrerequisiteBA(
+    __in INTERNAL_UI_BA_STATE* pState,
+    __in IBootstrapperEngine* pEngine,
+    __in const BOOTSTRAPPER_CREATE_ARGS* pArgs,
+    __inout BOOTSTRAPPER_CREATE_RESULTS* pResults
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczPrereqPath = NULL;
+    HMODULE hModule = NULL;
+
+    hr = PathConcat(pState->sczAppBase, L"prereqba.dll", &sczPrereqPath);
+    BalExitOnFailure(hr, "Failed to get path to pre-requisite BA.");
+
+    hModule = ::LoadLibraryExW(sczPrereqPath, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+    ExitOnNullWithLastError(hModule, hr, "Failed to load pre-requisite BA DLL.");
+
+    PFN_PREQ_BOOTSTRAPPER_APPLICATION_CREATE pfnCreate = reinterpret_cast<PFN_PREQ_BOOTSTRAPPER_APPLICATION_CREATE>(::GetProcAddress(hModule, "PrereqBootstrapperApplicationCreate"));
+    ExitOnNullWithLastError(pfnCreate, hr, "Failed to get PrereqBootstrapperApplicationCreate entry-point from: %ls", sczPrereqPath);
+
+    hr = pfnCreate(&pState->prereqData, pEngine, pArgs, pResults);
+    ExitOnFailure(hr, "Failed to create prequisite bootstrapper app.");
+
+    pState->hPrereqModule = hModule;
+    hModule = NULL;
+
+LExit:
+    if (hModule)
+    {
+        ::FreeLibrary(hModule);
+    }
+    ReleaseStr(sczPrereqPath);
+
+    return hr;
+}
diff --git a/src/ext/Bal/wixiuiba/wixiuiba.def b/src/ext/Bal/wixiuiba/wixiuiba.def
new file mode 100644
index 00000000..4488df94
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/wixiuiba.def
@@ -0,0 +1,6 @@
+; Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+
+EXPORTS
+    BootstrapperApplicationCreate
+    BootstrapperApplicationDestroy
diff --git a/src/ext/Bal/wixiuiba/wixiuiba.h b/src/ext/Bal/wixiuiba/wixiuiba.h
new file mode 100644
index 00000000..76077f42
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/wixiuiba.h
@@ -0,0 +1,13 @@
+#pragma once
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+
+struct INTERNAL_UI_BA_STATE
+{
+    BOOL fInitialized;
+    HINSTANCE hInstance;
+    LPWSTR sczAppBase;
+    HMODULE hPrereqModule;
+    PREQBA_DATA prereqData;
+    IBootstrapperApplication* pApplication;
+};
diff --git a/src/ext/Bal/wixiuiba/wixiuiba.vcxproj b/src/ext/Bal/wixiuiba/wixiuiba.vcxproj
new file mode 100644
index 00000000..dfadbb95
--- /dev/null
+++ b/src/ext/Bal/wixiuiba/wixiuiba.vcxproj
@@ -0,0 +1,72 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Project DefaultTargets="Build" Toolsxmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|ARM64">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM64">
+      <Configuration>Release</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{0F73E566-925C-448D-99CB-3A7F5DF399C8}</ProjectGuid>
+    <ConfigurationType>DynamicLibrary</ConfigurationType>
+    <CharacterSet>Unicode</CharacterSet>
+    <TargetName>wixiuiba</TargetName>
+    <ProjectModuleDefinitionFile>wixiuiba.def</ProjectModuleDefinitionFile>
+  </PropertyGroup>
+
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+
+  <PropertyGroup>
+    <ProjectAdditionalIncludeDirectories>..\wixstdba\inc</ProjectAdditionalIncludeDirectories>
+    <ProjectAdditionalLinkLibraries>shlwapi.lib</ProjectAdditionalLinkLibraries>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ClCompile Include="precomp.cpp">
+      <PrecompiledHeader>Create</PrecompiledHeader>
+    </ClCompile>
+    <ClCompile Include="WixInternalUIBootstrapperApplication.cpp" />
+    <ClCompile Include="wixiuiba.cpp" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="precomp.h" />
+    <ClInclude Include="WixInternalUIBootstrapperApplication.h" />
+    <ClInclude Include="wixiuiba.h" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="wixiuiba.def" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="WixToolset.BalUtil" />
+
+    <PackageReference Include="Microsoft.SourceLink.GitHub" PrivateAssets="All" />
+    <PackageReference Include="GitInfo" PrivateAssets="All" />
+  </ItemGroup>
+
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+</Project>
diff --git a/src/ext/Bal/wixlib/BalExtension_platform.wxi b/src/ext/Bal/wixlib/BalExtension_platform.wxi
index b2750eee..5b0d78d0 100644
--- a/src/ext/Bal/wixlib/BalExtension_platform.wxi
+++ b/src/ext/Bal/wixlib/BalExtension_platform.wxi
@@ -19,6 +19,20 @@
     </Fragment>
 
     <Fragment>
+        <BootstrapperApplication Id="WixInternalUIBootstrapperApplication$(var.Suffix)">
+            <BootstrapperApplicationDll Id="WixInternalUIBootstrapperApplication" SourceFile="!(bindpath.$(var.platform))\wixiuiba.dll" />
+            <Payload SourceFile="!(bindpath.$(var.platform))\wixstdba.dll" Name="prereqba.dll" />
+        </BootstrapperApplication>
+    </Fragment>
+
+    <Fragment>
+        <BootstrapperApplication Id="WixInternalUIBootstrapperApplication.Standard$(var.Suffix)">
+            <PayloadGroupRef Id="WixIuibaStandardPayloads" />
+        </BootstrapperApplication>
+        <BootstrapperApplicationRef Id="WixInternalUIBootstrapperApplication$(var.Suffix)" />
+    </Fragment>
+
+    <Fragment>
         <BootstrapperApplication Id="WixStandardBootstrapperApplication$(var.Suffix)">
             <BootstrapperApplicationDll Id="WixStandardBootstrapperApplication" SourceFile="!(bindpath.$(var.platform))\wixstdba.dll" />
         </BootstrapperApplication>
diff --git a/src/ext/Bal/wixlib/bal.wixproj b/src/ext/Bal/wixlib/bal.wixproj
index 627faecc..a7ae9a96 100644
--- a/src/ext/Bal/wixlib/bal.wixproj
+++ b/src/ext/Bal/wixlib/bal.wixproj
@@ -22,6 +22,9 @@
     <ProjectReference Include="..\mbahost\mbahost.vcxproj" Properties="Platform=x86" ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\mbahost\mbahost.vcxproj" Properties="Platform=x64" ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\mbahost\mbahost.vcxproj" Properties="Platform=ARM64" ReferenceOutputAssembly="false" />
+    <ProjectReference Include="..\wixiuiba\wixiuiba.vcxproj" Properties="Platform=x86" ReferenceOutputAssembly="false" />
+    <ProjectReference Include="..\wixiuiba\wixiuiba.vcxproj" Properties="Platform=x64" ReferenceOutputAssembly="false" />
+    <ProjectReference Include="..\wixiuiba\wixiuiba.vcxproj" Properties="Platform=ARM64" ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\wixstdba\wixstdba.vcxproj" Properties="Platform=x86" ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\wixstdba\wixstdba.vcxproj" Properties="Platform=x64" ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\wixstdba\wixstdba.vcxproj" Properties="Platform=ARM64" ReferenceOutputAssembly="false" />
diff --git a/src/ext/Bal/wixlib/wixiuiba.wxs b/src/ext/Bal/wixlib/wixiuiba.wxs
new file mode 100644
index 00000000..5501a23f
--- /dev/null
+++ b/src/ext/Bal/wixlib/wixiuiba.wxs
@@ -0,0 +1,12 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">
+    <Fragment>
+        <PayloadGroup Id="WixIuibaStandardPayloads">
+            <Payload Name="mbapreq.thm" SourceFile="!(wix.WixIuibaThemeXml=SourceDir\iuipreq.thm)" />
+            <Payload Name="mbapreq.png" SourceFile="!(wix.WixIuibaLogo=SourceDir\mbapreq.png)" />
+            <Payload Name="mbapreq.wxl" SourceFile="!(wix.WixIuibaThemeWxl=SourceDir\iuipreq.wxl)" />
+        </PayloadGroup>
+    </Fragment>
+</Wix>
diff --git a/src/ext/Bal/wixstdba/Resources/iuipreq.thm b/src/ext/Bal/wixstdba/Resources/iuipreq.thm
new file mode 100644
index 00000000..5429b3d2
--- /dev/null
+++ b/src/ext/Bal/wixstdba/Resources/iuipreq.thm
@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Theme xmlns="http://wixtoolset.org/schemas/v4/thmutil">
+    <Font Id="0" Height="-12" Weight="500" Foreground="windowtext" Background="window">Segoe UI</Font>
+    <Font Id="1" Height="-24" Weight="500" Foreground="windowtext">Segoe UI</Font>
+    <Font Id="2" Height="-22" Weight="500" Foreground="graytext">Segoe UI</Font>
+    <Font Id="3" Height="-12" Weight="500" Foreground="windowtext" Background="window">Segoe UI</Font>
+
+    <Window Width="485" Height="300" HexStyle="100a0000" FontId="0" Caption="#(loc.Caption)">
+        <ImageControl X="11" Y="11" Width="64" Height="64" ImageFile="mbapreq.png" Visible="yes"/>
+        <Label X="80" Y="11" Width="-11" Height="96" FontId="1" Visible="yes" DisablePrefix="yes">
+            <Text>#(loc.Title)</Text>
+            <Text Condition="WixBundleAction = 2 OR WixBundleCommandLineAction = 1">#(loc.NonPrereqTitle)</Text>
+        </Label>
+
+        <Page Name="Help">
+            <Label X="11" Y="112" Width="-11" Height="30" FontId="2" DisablePrefix="yes">#(loc.HelpHeader)</Label>
+            <Label X="11" Y="153" Width="-11" Height="-35" FontId="3" DisablePrefix="yes">#(loc.HelpText)</Label>
+            <Button Name="HelpCloseButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">
+                <Text>#(loc.HelpCloseButton)</Text>
+                <CloseWindowAction />
+            </Button>
+        </Page>
+        <Page Name="Install">
+            <Hypertext Name="EulaHyperlink" X="11" Y="121" Width="-11" Height="34" TabStop="yes" FontId="3">#(loc.InstallLicenseTerms)</Hypertext>
+            <Button Name="InstallButton" X="-91" Y="-11" Width="130" Height="23" TabStop="yes" FontId="0">#(loc.InstallAcceptAndInstallButton)</Button>
+            <Button Name="InstallDeclineButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">
+                <Text>#(loc.InstallDeclineButton)</Text>
+                <CloseWindowAction />
+            </Button>
+        </Page>
+        <Page Name="Progress">
+            <Label X="11" Y="112" Width="-11" Height="30" FontId="2" DisablePrefix="yes">#(loc.ProgressHeader)</Label>
+            <Label X="11" Y="153" Width="70" Height="17" FontId="3" DisablePrefix="yes">#(loc.ProgressLabel)</Label>
+            <Label Name="OverallProgressPackageText" X="85" Y="153" Width="-11" Height="17" FontId="3" DisablePrefix="yes">[ProgressPackageName]</Label>
+            <Progressbar Name="OverallCalculatedProgressbar" X="11" Y="175" Width="-11" Height="15" />
+            <Button Name="ProgressCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.ProgressCancelButton)</Button>
+        </Page>
+        <Page Name="Success">
+            <Label X="11" Y="112" Width="-11" Height="30" FontId="2" DisablePrefix="yes">
+                <Text>#(loc.SuccessHeader)</Text>
+                <Text Condition="WixBundleAction = 2">#(loc.SuccessLayoutHeader)</Text>
+            </Label>
+            <Label X="-11" Y="-20" Width="400" Height="34" FontId="3" DisablePrefix="yes" VisibleCondition="WixStdBARestartRequired">
+                <Text>#(loc.SuccessRestartText)</Text>
+            </Label>
+            <Button Name="SuccessRestartButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.SuccessRestartButton)</Button>
+            <Button Name="SuccessCloseButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">
+                <Text>#(loc.SuccessCloseButton)</Text>
+                <CloseWindowAction />
+            </Button>
+        </Page>
+        <Page Name="Failure">
+            <Label X="11" Y="112" Width="-11" Height="30" FontId="2" DisablePrefix="yes">
+                <Text>#(loc.FailureHeader)</Text>
+                <Text Condition="WixBundleAction = 2">#(loc.FailureLayoutHeader)</Text>
+            </Label>
+            <Hypertext Name="FailureLogFileLink" X="11" Y="153" Width="-11" Height="51" FontId="3" TabStop="yes" HideWhenDisabled="yes">#(loc.FailureLogLinkText)</Hypertext>
+            <Hypertext Name="FailureMessageText" X="22" Y="190" Width="-11" Height="51" FontId="3" TabStop="yes" HideWhenDisabled="yes"/>
+            <Label X="-11" Y="-20" Width="400" Height="34" FontId="3" DisablePrefix="yes" VisibleCondition="WixStdBARestartRequired">#(loc.FailureRestartText)</Label>
+            <Button Name="FailureRestartButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.FailureRestartButton)</Button>
+            <Button Name="FailureCloseButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">
+                <Text>#(loc.FailureCloseButton)</Text>
+                <CloseWindowAction />
+            </Button>
+        </Page>
+    </Window>
+</Theme>
diff --git a/src/ext/Bal/wixstdba/Resources/iuipreq.wxl b/src/ext/Bal/wixstdba/Resources/iuipreq.wxl
new file mode 100644
index 00000000..4afcd10f
--- /dev/null
+++ b/src/ext/Bal/wixstdba/Resources/iuipreq.wxl
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+
+<WixLocalization Culture="en-us" Language="1033" xmlns="http://wixtoolset.org/schemas/v4/wxl">
+  <String Id="Caption">[WixBundleName] Prerequisite Setup</String>
+  <String Id="Title">Prerequisite required for [WixBundleName] setup</String>
+  <String Id="NonPrereqTitle">[WixBundleName] setup</String>
+  <String Id="ConfirmCancelMessage">Are you sure you want to cancel?</String>
+  <String Id="HelpHeader">Setup Help</String>
+  <String Id="HelpText">/passive | /quiet -  displays minimal UI with no prompts or displays no UI and
+   no prompts. By default UI and all prompts are displayed.
+
+/log log.txt - logs to a specific file. By default a log file is created in %TEMP%.</String>
+  <String Id="HelpCloseButton">&amp;Close</String>
+  <String Id="InstallLicenseTerms">Click the "Accept and Install" button to accept the prerequisite &lt;a href="#"&gt;license terms&lt;/a&gt;.</String>
+  <String Id="InstallAcceptAndInstallButton">&amp;Accept and Install</String>
+  <String Id="InstallDeclineButton">&amp;Decline</String>
+  <String Id="ProgressHeader">Setup Progress</String>
+  <String Id="ProgressLabel">Processing:</String>
+  <String Id="ProgressCancelButton">&amp;Cancel</String>
+  <String Id="SuccessHeader">Prerequisite Setup Successful</String>
+  <String Id="SuccessLayoutHeader">Layout Successfully Completed</String>
+  <String Id="SuccessRestartText">You must restart your computer before [WixBundleName] setup can continue.</String>
+  <String Id="SuccessRestartButton">&amp;Restart</String>
+  <String Id="SuccessCloseButton">&amp;Close</String>
+  <String Id="FailureHeader">Setup Failed</String>
+  <String Id="FailureLayoutHeader">Layout Failed</String>
+  <String Id="FailureLogLinkText">One or more issues caused the setup to fail. Please fix the issues and then retry setup. For more information see the &lt;a href="#"&gt;log file&lt;/a&gt;.</String>
+  <String Id="FailureRestartText">You must restart your computer to complete the rollback of the software.</String>
+  <String Id="FailureRestartButton">&amp;Restart</String>
+  <String Id="FailureCloseButton">&amp;Close</String>
+  <String Id="ErrorFailNoActionReboot">No action was taken as a system reboot is required.</String>
+</WixLocalization>
diff --git a/src/ext/Bal/wixstdba/WixStandardBootstrapperApplication.cpp b/src/ext/Bal/wixstdba/WixStandardBootstrapperApplication.cpp
index 9aa58a28..1af1abeb 100644
--- a/src/ext/Bal/wixstdba/WixStandardBootstrapperApplication.cpp
+++ b/src/ext/Bal/wixstdba/WixStandardBootstrapperApplication.cpp
@@ -248,10 +248,20 @@ public: // IBootstrapperApplication
 
         if (m_fPrereq)
         {
-            // Pre-req BA should only show help or do an install (to launch the Managed BA which can then do the right action).
-            if (BOOTSTRAPPER_ACTION_HELP != m_command.action)
+            if (m_pPrereqData->fPerformLayout && BOOTSTRAPPER_ACTION_LAYOUT == m_command.action)
             {
-                m_command.action = BOOTSTRAPPER_ACTION_INSTALL;
+                // The parent BA has requested that this BA be in charge of layout.
+                m_fPrereq = FALSE;
+            }
+            else
+            {
+                m_fPreplanPrereqs = m_pPrereqData->fAlwaysInstallPrereqs;
+
+                // Pre-req BA should only show help or do an install (to launch the parent BA which can then do the right action).
+                if (BOOTSTRAPPER_ACTION_HELP != m_command.action)
+                {
+                    m_command.action = BOOTSTRAPPER_ACTION_INSTALL;
+                }
             }
         }
         else // maybe modify the action state if the bundle is or is not already installed.
@@ -527,11 +537,11 @@ public: // IBootstrapperApplication
         )
     {
         HRESULT hr = S_OK;
-        BOOL fPlannedPrereqs = WIXSTDBA_STATE_PLANNING_PREREQS == m_state;
+        BOOL fPreplannedPrereqs = WIXSTDBA_STATE_PLANNING_PREREQS == m_state;
         WIXSTDBA_STATE completedState = WIXSTDBA_STATE_PLANNED;
         BOOL fApply = TRUE;
 
-        if (fPlannedPrereqs)
+        if (fPreplannedPrereqs)
         {
             if (SUCCEEDED(hrStatus) && !m_fPrereqPackagePlanned)
             {
@@ -547,7 +557,7 @@ public: // IBootstrapperApplication
                 // Need to force the state change since normally moving backwards is prevented.
                 ::PostMessageW(m_hWnd, WM_WIXSTDBA_CHANGE_STATE, 0, WIXSTDBA_STATE_HELP);
 
-                ::PostMessageW(m_hWnd, WM_WIXSTDBA_SHOW_HELP, 0, 0);                
+                ::PostMessageW(m_hWnd, WM_WIXSTDBA_SHOW_HELP, 0, 0);
 
                 ExitFunction();
             }
@@ -562,7 +572,7 @@ public: // IBootstrapperApplication
             ExitFunction();
         }
 
-        if (fPlannedPrereqs)
+        if (fPreplannedPrereqs)
         {
             // If the UI should be visible, display it now and hide the splash screen
             if (BOOTSTRAPPER_DISPLAY_NONE < m_command.display)
@@ -1056,13 +1066,14 @@ public: // IBootstrapperApplication
 
         hr = __super::OnExecutePackageComplete(wzPackageId, hrStatus, restart, recommendation, pAction);
 
-        BAL_INFO_PACKAGE* pPackage = NULL;
-        HRESULT hrPrereq = BalInfoFindPackageById(&m_Bundle.packages, wzPackageId, &pPackage);
-        if (SUCCEEDED(hrPrereq))
+        if (m_fPrereq && BOOTSTRAPPER_APPLY_RESTART_NONE != restart)
         {
+            BAL_INFO_PACKAGE* pPackage = NULL;
+            HRESULT hrPrereq = BalInfoFindPackageById(&m_Bundle.packages, wzPackageId, &pPackage);
+
             // If the prerequisite required a restart (any restart) then do an immediate
             // restart to ensure that the bundle will get launched again post reboot.
-            if (m_fPrereq && pPackage->fPrereqPackage && BOOTSTRAPPER_APPLY_RESTART_NONE != restart)
+            if (SUCCEEDED(hrPrereq) && pPackage->fPrereqPackage)
             {
                 *pAction = BOOTSTRAPPER_EXECUTEPACKAGECOMPLETE_ACTION_RESTART;
             }
@@ -2283,7 +2294,7 @@ private:
             // Okay, we're ready for packages now.
             pThis->SetState(WIXSTDBA_STATE_INITIALIZED, hr);
 
-            if (!pThis->m_fPreplanPrereqs && BOOTSTRAPPER_ACTION_HELP == pThis->m_command.action)
+            if (pThis->m_fPerformHelp && BOOTSTRAPPER_ACTION_HELP == pThis->m_command.action)
             {
                 firstAction = WM_WIXSTDBA_SHOW_HELP;
             }
@@ -4246,7 +4257,7 @@ public:
         m_hWnd = NULL;
 
         m_state = WIXSTDBA_STATE_INITIALIZING;
-        m_hrFinal = pPrereqData ? pPrereqData->hrHostInitialization : S_OK;
+        m_hrFinal = pPrereqData ? pPrereqData->hrFatalError : S_OK;
 
         m_restartResult = BOOTSTRAPPER_APPLY_RESTART_NONE;
         m_fRestartRequired = FALSE;
@@ -4269,7 +4280,8 @@ public:
 
         m_pPrereqData = pPrereqData;
         m_fPrereq = NULL != pPrereqData;
-        m_fPreplanPrereqs = m_fPrereq && m_pPrereqData->fAlwaysInstallPrereqs;
+        m_fPreplanPrereqs = FALSE;
+        m_fPerformHelp = !m_fPrereq || m_pPrereqData->fPerformHelp;
         m_fPrereqPackagePlanned = FALSE;
         m_fPrereqInstalled = FALSE;
         m_fPrereqSkipped = FALSE;
@@ -4554,6 +4566,7 @@ private:
     PREQBA_DATA* m_pPrereqData;
     BOOL m_fPrereq;
     BOOL m_fPreplanPrereqs;
+    BOOL m_fPerformHelp;
     BOOL m_fPrereqPackagePlanned;
     BOOL m_fPrereqInstalled;
     BOOL m_fPrereqSkipped;
diff --git a/src/ext/Bal/wixstdba/inc/preqba.h b/src/ext/Bal/wixstdba/inc/preqba.h
index ed339730..25fa7105 100644
--- a/src/ext/Bal/wixstdba/inc/preqba.h
+++ b/src/ext/Bal/wixstdba/inc/preqba.h
@@ -4,8 +4,10 @@
 
 struct PREQBA_DATA
 {
-    HRESULT hrHostInitialization;
+    HRESULT hrFatalError;
     BOOL fAlwaysInstallPrereqs;
+    BOOL fPerformHelp;
+    BOOL fPerformLayout;
     BOOL fCompleted;
 };
 
diff --git a/src/test/burn/TestData/Templates/Bundle.wxs b/src/test/burn/TestData/Templates/Bundle.wxs
index 612e67f5..c55f67a7 100644
--- a/src/test/burn/TestData/Templates/Bundle.wxs
+++ b/src/test/burn/TestData/Templates/Bundle.wxs
@@ -33,6 +33,10 @@
       <BootstrapperApplication>
         <bal:WixStandardBootstrapperApplication LicenseUrl="" Theme="hyperlinkLicense" />
       </BootstrapperApplication>
+    <?elseif $(var.BA) = "iui"?>
+      <BootstrapperApplication>
+        <bal:WixInternalUIBootstrapperApplication />
+      </BootstrapperApplication>
     <?else?>
       <BootstrapperApplicationRef Id="$(var.BA)" />
     <?endif?>
diff --git a/src/test/burn/TestData/TestData.proj b/src/test/burn/TestData/TestData.proj
index 27bfb02b..0f7cbee9 100644
--- a/src/test/burn/TestData/TestData.proj
+++ b/src/test/burn/TestData/TestData.proj
@@ -4,7 +4,7 @@
 <Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
     <TestDataProject Include="**\*.wixproj" />
-    
+
     <!-- https://github.com/wixtoolset/issues/issues/6401 -->
     <TestDataProject Remove="DependencyTests\BundleC\BundleC.wixproj" />
     <TestDataProject Remove="DependencyTests\BundleF_PatchAv1_0_1\BundleF_PatchAv1_0_1.wixproj" />
diff --git a/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/ArchSpecificBundle.wixproj b/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/ArchSpecificBundle.wixproj
new file mode 100644
index 00000000..9e3cba8b
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/ArchSpecificBundle.wixproj
@@ -0,0 +1,17 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <OutputType>Bundle</OutputType>
+    <BA>iui</BA>
+    <UpgradeCode>{22B5ADAF-74D3-424A-8D32-9901FCF97E6D}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\InternalUIPackage\InternalUIPackage.wixproj" />
+    <ProjectReference Include="..\InternalUIarm64Package\InternalUIarm64Package.wixproj" />
+    <ProjectReference Include="..\InternalUIx64Package\InternalUIx64Package.wixproj" />
+    <ProjectReference Include="..\InternalUIx86Package\InternalUIx86Package.wixproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.Bal.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/ArchSpecificBundle.wxs b/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/ArchSpecificBundle.wxs
new file mode 100644
index 00000000..71b8665f
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/ArchSpecificBundle.wxs
@@ -0,0 +1,13 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+  <Fragment>
+    <PackageGroup Id="BundlePackages">
+      <MsiPackage Id="InternalUIPackage" SourceFile="$(var.InternalUIPackage.TargetPath)" />
+      <MsiPackage Id="InternalUIarm64Package" SourceFile="$(var.InternalUIarm64Package.TargetPath)" bal:PrimaryPackageType="arm64" />
+      <MsiPackage Id="InternalUIx64Package" SourceFile="$(var.InternalUIx64Package.TargetPath)" bal:PrimaryPackageType="x64" />
+      <MsiPackage Id="InternalUIx86Package" SourceFile="$(var.InternalUIx86Package.TargetPath)" bal:PrimaryPackageType="x86" />
+    </PackageGroup>
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/Bundle.wxs b/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/Bundle.wxs
new file mode 100644
index 00000000..195c159e
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/ArchSpecificBundle/Bundle.wxs
@@ -0,0 +1,63 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<?ifndef Version?>
+<?define Version = 1.0.0.0?>
+<?endif?>
+<?ifndef BundleLogDirectory?>
+<?define BundleLogDirectory = .?>
+<?endif?>
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+  <!-- The only difference from the template should be the SplashScreen and uncompressed -->
+  <Bundle Name="~$(var.TestGroupName) - $(var.BundleName)" Version="$(var.Version)" UpgradeCode="$(var.UpgradeCode)" Compressed="no" SplashScreenSourceFile="..\..\Manual\BafThmutilTesting\theme\star_transparent.bmp">
+    <Log Prefix="$(var.BundleLogDirectory)\~$(var.TestGroupName)_$(var.BundleName)" />
+
+    <Variable Name="TestGroupName" Value="$(var.TestGroupName)" />
+
+    <?ifdef SoftwareTag?>
+    <SoftwareTag Regid="regid.1995-08.com.example" InstallPath="[CommonAppDataFolder]regid.1995-08.com.example" />
+    <?endif?>
+
+    <?ifndef BA?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBAdnc"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBA_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBAdnc_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "WixBA"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "WixBAdnc_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "hyperlinkLicense"?>
+      <BootstrapperApplication>
+        <bal:WixStandardBootstrapperApplication LicenseUrl="" Theme="hyperlinkLicense" />
+      </BootstrapperApplication>
+    <?elseif $(var.BA) = "iui"?>
+      <BootstrapperApplication>
+        <bal:WixInternalUIBootstrapperApplication />
+      </BootstrapperApplication>
+    <?else?>
+      <BootstrapperApplicationRef Id="$(var.BA)" />
+    <?endif?>
+
+    <Chain>
+      <?ifndef BA?>
+        <PackageGroupRef Id="TestBA" />
+      <?elseif $(var.BA) = "TestBAdnc"?>
+        <PackageGroupRef Id="TestBAdnc" />
+      <?elseif $(var.BA) = "TestBA_x64"?>
+        <PackageGroupRef Id="TestBA_x64" />
+      <?elseif $(var.BA) = "TestBAdnc_x64"?>
+        <PackageGroupRef Id="TestBAdnc_x64" />
+      <?elseif $(var.BA) = "WixBA"?>
+        <PackageGroupRef Id="WixBA" />
+      <?elseif $(var.BA) = "WixBAdnc_x64"?>
+        <PackageGroupRef Id="WixBAdnc_x64" />
+      <?endif?>
+
+      <PackageGroupRef Id="BundlePackages" />
+    </Chain>
+  </Bundle>
+</Wix>
diff --git a/src/test/dtf/DtfE2ETests.sln b/src/test/burn/TestData/WixIuiBaTests/DtfSamples.sln
index 39d8cf08..1e6c2082 100644
--- a/src/test/dtf/DtfE2ETests.sln
+++ b/src/test/burn/TestData/WixIuiBaTests/DtfSamples.sln
@@ -5,7 +5,7 @@ VisualStudioVersion = 16.0.30114.105
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EmbeddedUI", "EmbeddedUI\EmbeddedUI.csproj", "{864B8C50-7895-4485-AC89-900D86FD8C0D}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SampleCA", "SampleCA\SampleCA.csproj", "{8F53B9CC-6FBE-493D-9C9A-09B2AD578CE7}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ManagedCA", "ManagedCA\ManagedCA.csproj", "{8F53B9CC-6FBE-493D-9C9A-09B2AD578CE7}"
 EndProject
 Global
         GlobalSection(SolutionConfigurationPlatforms) = preSolution
diff --git a/src/test/dtf/EmbeddedUI/EmbeddedUI.config b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/EmbeddedUI.config
index 700aff6f..700aff6f 100644
--- a/src/test/dtf/EmbeddedUI/EmbeddedUI.config
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/EmbeddedUI.config
diff --git a/src/test/dtf/EmbeddedUI/EmbeddedUI.csproj b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/EmbeddedUI.csproj
index a6339220..a6339220 100644
--- a/src/test/dtf/EmbeddedUI/EmbeddedUI.csproj
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/EmbeddedUI.csproj
diff --git a/src/test/dtf/EmbeddedUI/InstallProgressCounter.cs b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/InstallProgressCounter.cs
index 3d75081c..3d75081c 100644
--- a/src/test/dtf/EmbeddedUI/InstallProgressCounter.cs
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/InstallProgressCounter.cs
diff --git a/src/test/dtf/EmbeddedUI/SampleEmbeddedUI.cs b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/SampleEmbeddedUI.cs
index ae86dc97..ae86dc97 100644
--- a/src/test/dtf/EmbeddedUI/SampleEmbeddedUI.cs
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/SampleEmbeddedUI.cs
diff --git a/src/test/dtf/EmbeddedUI/SetupWizard.xaml b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/SetupWizard.xaml
index 97e406c2..97e406c2 100644
--- a/src/test/dtf/EmbeddedUI/SetupWizard.xaml
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/SetupWizard.xaml
diff --git a/src/test/dtf/EmbeddedUI/SetupWizard.xaml.cs b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/SetupWizard.xaml.cs
index a4345481..a4345481 100644
--- a/src/test/dtf/EmbeddedUI/SetupWizard.xaml.cs
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUI/SetupWizard.xaml.cs
diff --git a/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/Bundle.wxs b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/Bundle.wxs
new file mode 100644
index 00000000..195c159e
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/Bundle.wxs
@@ -0,0 +1,63 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<?ifndef Version?>
+<?define Version = 1.0.0.0?>
+<?endif?>
+<?ifndef BundleLogDirectory?>
+<?define BundleLogDirectory = .?>
+<?endif?>
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+  <!-- The only difference from the template should be the SplashScreen and uncompressed -->
+  <Bundle Name="~$(var.TestGroupName) - $(var.BundleName)" Version="$(var.Version)" UpgradeCode="$(var.UpgradeCode)" Compressed="no" SplashScreenSourceFile="..\..\Manual\BafThmutilTesting\theme\star_transparent.bmp">
+    <Log Prefix="$(var.BundleLogDirectory)\~$(var.TestGroupName)_$(var.BundleName)" />
+
+    <Variable Name="TestGroupName" Value="$(var.TestGroupName)" />
+
+    <?ifdef SoftwareTag?>
+    <SoftwareTag Regid="regid.1995-08.com.example" InstallPath="[CommonAppDataFolder]regid.1995-08.com.example" />
+    <?endif?>
+
+    <?ifndef BA?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBAdnc"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBA_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBAdnc_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "WixBA"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "WixBAdnc_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "hyperlinkLicense"?>
+      <BootstrapperApplication>
+        <bal:WixStandardBootstrapperApplication LicenseUrl="" Theme="hyperlinkLicense" />
+      </BootstrapperApplication>
+    <?elseif $(var.BA) = "iui"?>
+      <BootstrapperApplication>
+        <bal:WixInternalUIBootstrapperApplication />
+      </BootstrapperApplication>
+    <?else?>
+      <BootstrapperApplicationRef Id="$(var.BA)" />
+    <?endif?>
+
+    <Chain>
+      <?ifndef BA?>
+        <PackageGroupRef Id="TestBA" />
+      <?elseif $(var.BA) = "TestBAdnc"?>
+        <PackageGroupRef Id="TestBAdnc" />
+      <?elseif $(var.BA) = "TestBA_x64"?>
+        <PackageGroupRef Id="TestBA_x64" />
+      <?elseif $(var.BA) = "TestBAdnc_x64"?>
+        <PackageGroupRef Id="TestBAdnc_x64" />
+      <?elseif $(var.BA) = "WixBA"?>
+        <PackageGroupRef Id="WixBA" />
+      <?elseif $(var.BA) = "WixBAdnc_x64"?>
+        <PackageGroupRef Id="WixBAdnc_x64" />
+      <?endif?>
+
+      <PackageGroupRef Id="BundlePackages" />
+    </Chain>
+  </Bundle>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/EmbeddedUIBundle.wixproj b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/EmbeddedUIBundle.wixproj
new file mode 100644
index 00000000..7c856200
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/EmbeddedUIBundle.wixproj
@@ -0,0 +1,15 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <OutputType>Bundle</OutputType>
+    <BA>iui</BA>
+    <UpgradeCode>{5115D6AC-A1FE-40C6-BEB3-BEBB39E61579}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\EmbeddedUIPackage\EmbeddedUIPackage.wixproj" />
+    <ProjectReference Include="..\InternalUIPackage\InternalUIPackage.wixproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.Bal.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/EmbeddedUIBundle.wxs b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/EmbeddedUIBundle.wxs
new file mode 100644
index 00000000..6adda9de
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIBundle/EmbeddedUIBundle.wxs
@@ -0,0 +1,11 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">
+  <Fragment>
+    <PackageGroup Id="BundlePackages">
+      <MsiPackage Id="InternalUIPackage" SourceFile="$(var.InternalUIPackage.TargetPath)" Permanent="yes" />
+      <MsiPackage Id="EmbeddedUIPackage" SourceFile="$(var.EmbeddedUIPackage.TargetPath)" />
+    </PackageGroup>
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIPackage/EmbeddedUIPackage.wixproj b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIPackage/EmbeddedUIPackage.wixproj
new file mode 100644
index 00000000..0a62f38b
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIPackage/EmbeddedUIPackage.wixproj
@@ -0,0 +1,16 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <ProductComponentsRef>true</ProductComponentsRef>
+    <UpgradeCode>{A6826B6D-2F3F-456D-BABF-1B8CDCE3AE68}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Package.wxs" Link="Package.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\EmbeddedUI\EmbeddedUI.csproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.UI.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIPackage/EmbeddedUIPackage.wxs b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIPackage/EmbeddedUIPackage.wxs
new file mode 100644
index 00000000..e5d18c80
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/EmbeddedUIPackage/EmbeddedUIPackage.wxs
@@ -0,0 +1,13 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:ui="http://wixtoolset.org/schemas/v4/wxs/ui">
+  <Fragment>
+    <ComponentGroup Id="ProductComponents" />
+
+    <ui:WixUI Id="WixUI_Minimal" />
+
+    <UI>
+      <EmbeddedUI SourceFile="$(var.EmbeddedUI.TargetDir)$(var.EmbeddedUI.TargetName).CA.dll" />
+    </UI>
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/Bundle.wxs b/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/Bundle.wxs
new file mode 100644
index 00000000..195c159e
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/Bundle.wxs
@@ -0,0 +1,63 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<?ifndef Version?>
+<?define Version = 1.0.0.0?>
+<?endif?>
+<?ifndef BundleLogDirectory?>
+<?define BundleLogDirectory = .?>
+<?endif?>
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:bal="http://wixtoolset.org/schemas/v4/wxs/bal">
+  <!-- The only difference from the template should be the SplashScreen and uncompressed -->
+  <Bundle Name="~$(var.TestGroupName) - $(var.BundleName)" Version="$(var.Version)" UpgradeCode="$(var.UpgradeCode)" Compressed="no" SplashScreenSourceFile="..\..\Manual\BafThmutilTesting\theme\star_transparent.bmp">
+    <Log Prefix="$(var.BundleLogDirectory)\~$(var.TestGroupName)_$(var.BundleName)" />
+
+    <Variable Name="TestGroupName" Value="$(var.TestGroupName)" />
+
+    <?ifdef SoftwareTag?>
+    <SoftwareTag Regid="regid.1995-08.com.example" InstallPath="[CommonAppDataFolder]regid.1995-08.com.example" />
+    <?endif?>
+
+    <?ifndef BA?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBAdnc"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBA_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "TestBAdnc_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "WixBA"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "WixBAdnc_x64"?>
+      <!-- pulled in through the PackageGroupRef below -->
+    <?elseif $(var.BA) = "hyperlinkLicense"?>
+      <BootstrapperApplication>
+        <bal:WixStandardBootstrapperApplication LicenseUrl="" Theme="hyperlinkLicense" />
+      </BootstrapperApplication>
+    <?elseif $(var.BA) = "iui"?>
+      <BootstrapperApplication>
+        <bal:WixInternalUIBootstrapperApplication />
+      </BootstrapperApplication>
+    <?else?>
+      <BootstrapperApplicationRef Id="$(var.BA)" />
+    <?endif?>
+
+    <Chain>
+      <?ifndef BA?>
+        <PackageGroupRef Id="TestBA" />
+      <?elseif $(var.BA) = "TestBAdnc"?>
+        <PackageGroupRef Id="TestBAdnc" />
+      <?elseif $(var.BA) = "TestBA_x64"?>
+        <PackageGroupRef Id="TestBA_x64" />
+      <?elseif $(var.BA) = "TestBAdnc_x64"?>
+        <PackageGroupRef Id="TestBAdnc_x64" />
+      <?elseif $(var.BA) = "WixBA"?>
+        <PackageGroupRef Id="WixBA" />
+      <?elseif $(var.BA) = "WixBAdnc_x64"?>
+        <PackageGroupRef Id="WixBAdnc_x64" />
+      <?endif?>
+
+      <PackageGroupRef Id="BundlePackages" />
+    </Chain>
+  </Bundle>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/InternalUIBundle.wixproj b/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/InternalUIBundle.wixproj
new file mode 100644
index 00000000..193d0ca6
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/InternalUIBundle.wixproj
@@ -0,0 +1,14 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <OutputType>Bundle</OutputType>
+    <BA>iui</BA>
+    <UpgradeCode>{62CB2BAE-129D-41D1-928B-5353FC542130}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\InternalUIPackage\InternalUIPackage.wixproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.Bal.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/InternalUIBundle.wxs b/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/InternalUIBundle.wxs
new file mode 100644
index 00000000..332f0b08
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIBundle/InternalUIBundle.wxs
@@ -0,0 +1,10 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">
+  <Fragment>
+    <PackageGroup Id="BundlePackages">
+      <MsiPackage Id="InternalUIPackage" SourceFile="$(var.InternalUIPackage.TargetPath)" />
+    </PackageGroup>
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIPackage/InternalUIPackage.wixproj b/src/test/burn/TestData/WixIuiBaTests/InternalUIPackage/InternalUIPackage.wixproj
new file mode 100644
index 00000000..2744d4b3
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIPackage/InternalUIPackage.wixproj
@@ -0,0 +1,16 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <ProductComponentsRef>true</ProductComponentsRef>
+    <UpgradeCode>{7A0FE267-9EAE-4780-B41E-60C9E7044F53}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Package.wxs" Link="Package.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\ManagedCA\ManagedCA.csproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.UI.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIPackage/InternalUIPackage.wxs b/src/test/burn/TestData/WixIuiBaTests/InternalUIPackage/InternalUIPackage.wxs
new file mode 100644
index 00000000..d5f30729
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIPackage/InternalUIPackage.wxs
@@ -0,0 +1,24 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:ui="http://wixtoolset.org/schemas/v4/wxs/ui">
+  <Fragment>
+    <ComponentGroup Id="ProductComponents" />
+
+    <ui:WixUI Id="WixUI_Minimal" />
+
+    <Binary Id="TestData" SourceFile="$(var.ManagedCA.TargetDir)testsub\testfile.txt" />
+    <Binary Id="ManagedCA" SourceFile="$(var.ManagedCA.TargetDir)$(var.ManagedCA.TargetName).CA.dll" />
+    <CustomAction Id="SampleCA1" BinaryRef="ManagedCA" DllEntry="SampleCA1" Execute="firstSequence" />
+    <CustomAction Id="SampleCustomAction2" BinaryRef="ManagedCA" DllEntry="SampleCA2" Execute="firstSequence" Return="ignore" />
+
+    <InstallUISequence>
+      <Custom Action="SampleCA1" After="CostFinalize" Condition="NOT Installed" />
+      <Custom Action="SampleCustomAction2" After="SampleCA1" Condition="NOT Installed" />
+    </InstallUISequence>
+
+    <InstallExecuteSequence>
+      <Custom Action="SampleCA1" After="CostFinalize" Condition="NOT Installed" />
+      <Custom Action="SampleCustomAction2" After="SampleCA1" Condition="NOT Installed" />
+    </InstallExecuteSequence>
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIarm64Package/InternalUIarm64Package.wixproj b/src/test/burn/TestData/WixIuiBaTests/InternalUIarm64Package/InternalUIarm64Package.wixproj
new file mode 100644
index 00000000..e7d5b484
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIarm64Package/InternalUIarm64Package.wixproj
@@ -0,0 +1,14 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <InstallerPlatform>arm64</InstallerPlatform>
+    <ProductComponentsRef>true</ProductComponentsRef>
+    <UpgradeCode>{357EBF93-039C-4378-8BCB-8B53F9B9F69A}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Package.wxs" Link="Package.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.UI.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIarm64Package/InternalUIarm64Package.wxs b/src/test/burn/TestData/WixIuiBaTests/InternalUIarm64Package/InternalUIarm64Package.wxs
new file mode 100644
index 00000000..c30cf607
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIarm64Package/InternalUIarm64Package.wxs
@@ -0,0 +1,9 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:ui="http://wixtoolset.org/schemas/v4/wxs/ui">
+  <Fragment>
+    <ComponentGroup Id="ProductComponents" />
+
+    <ui:WixUI Id="WixUI_Minimal" />
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIx64Package/InternalUIx64Package.wixproj b/src/test/burn/TestData/WixIuiBaTests/InternalUIx64Package/InternalUIx64Package.wixproj
new file mode 100644
index 00000000..ff646914
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIx64Package/InternalUIx64Package.wixproj
@@ -0,0 +1,14 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <InstallerPlatform>x64</InstallerPlatform>
+    <ProductComponentsRef>true</ProductComponentsRef>
+    <UpgradeCode>{2EBACF8F-BECD-401C-94F2-CFA2C9C3C07F}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Package.wxs" Link="Package.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.UI.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIx64Package/InternalUIx64Package.wxs b/src/test/burn/TestData/WixIuiBaTests/InternalUIx64Package/InternalUIx64Package.wxs
new file mode 100644
index 00000000..c30cf607
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIx64Package/InternalUIx64Package.wxs
@@ -0,0 +1,9 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:ui="http://wixtoolset.org/schemas/v4/wxs/ui">
+  <Fragment>
+    <ComponentGroup Id="ProductComponents" />
+
+    <ui:WixUI Id="WixUI_Minimal" />
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIx86Package/InternalUIx86Package.wixproj b/src/test/burn/TestData/WixIuiBaTests/InternalUIx86Package/InternalUIx86Package.wixproj
new file mode 100644
index 00000000..4107ab44
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIx86Package/InternalUIx86Package.wixproj
@@ -0,0 +1,14 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <InstallerPlatform>x64</InstallerPlatform>
+    <ProductComponentsRef>true</ProductComponentsRef>
+    <UpgradeCode>{1FA46DA0-5F83-459A-8A30-3E5A54D20A4D}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Package.wxs" Link="Package.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.UI.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/WixIuiBaTests/InternalUIx86Package/InternalUIx86Package.wxs b/src/test/burn/TestData/WixIuiBaTests/InternalUIx86Package/InternalUIx86Package.wxs
new file mode 100644
index 00000000..c30cf607
--- /dev/null
+++ b/src/test/burn/TestData/WixIuiBaTests/InternalUIx86Package/InternalUIx86Package.wxs
@@ -0,0 +1,9 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs" xmlns:ui="http://wixtoolset.org/schemas/v4/wxs/ui">
+  <Fragment>
+    <ComponentGroup Id="ProductComponents" />
+
+    <ui:WixUI Id="WixUI_Minimal" />
+  </Fragment>
+</Wix>
diff --git a/src/test/dtf/SampleCA/CustomAction.config b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/CustomAction.config
index 700aff6f..700aff6f 100644
--- a/src/test/dtf/SampleCA/CustomAction.config
+++ b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/CustomAction.config
diff --git a/src/test/dtf/SampleCA/SampleCA.csproj b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/ManagedCA.csproj
index 866b7575..866b7575 100644
--- a/src/test/dtf/SampleCA/SampleCA.csproj
+++ b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/ManagedCA.csproj
diff --git a/src/test/dtf/SampleCA/SampleCA.cs b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/SampleCA.cs
index fc9f30fe..fc9f30fe 100644
--- a/src/test/dtf/SampleCA/SampleCA.cs
+++ b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/SampleCA.cs
diff --git a/src/test/dtf/SampleCA/testsub/testfile.txt b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/testsub/testfile.txt
index 8056aefd..8056aefd 100644
--- a/src/test/dtf/SampleCA/testsub/testfile.txt
+++ b/src/test/burn/TestData/WixIuiBaTests/ManagedCA/testsub/testfile.txt
diff --git a/src/test/burn/WixTestTools/PackageVerifier.cs b/src/test/burn/WixTestTools/PackageVerifier.cs
index fd8378e0..4545b9ec 100644
--- a/src/test/burn/WixTestTools/PackageVerifier.cs
+++ b/src/test/burn/WixTestTools/PackageVerifier.cs
@@ -63,17 +63,27 @@ namespace WixTestTools
             return row.Value;
         }
 
-        public void VerifyInstalled(bool installed)
+        public bool IsInstalled()
         {
             var productCode = this.GetProperty("ProductCode");
-            Assert.Equal(installed, MsiUtilities.IsProductInstalled(productCode));
+            return MsiUtilities.IsProductInstalled(productCode);
         }
 
-        public void VerifyInstalledWithVersion(bool installed)
+        public bool IsInstalledWithVersion()
         {
             var productCode = this.GetProperty("ProductCode");
             Version prodVersion = new Version(this.GetProperty("ProductVersion"));
-            Assert.Equal(installed, MsiUtilities.IsProductInstalledWithVersion(productCode, prodVersion));
+            return MsiUtilities.IsProductInstalledWithVersion(productCode, prodVersion);
+        }
+
+        public void VerifyInstalled(bool installed)
+        {
+            Assert.Equal(installed, this.IsInstalled());
+        }
+
+        public void VerifyInstalledWithVersion(bool installed)
+        {
+            Assert.Equal(installed, this.IsInstalledWithVersion());
         }
 
         public void DeleteTestRegistryValue(string name)
diff --git a/src/test/burn/WixToolsetTest.BurnE2E/WixIuiBaTests.cs b/src/test/burn/WixToolsetTest.BurnE2E/WixIuiBaTests.cs
new file mode 100644
index 00000000..18dd41db
--- /dev/null
+++ b/src/test/burn/WixToolsetTest.BurnE2E/WixIuiBaTests.cs
@@ -0,0 +1,144 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolsetTest.BurnE2E
+{
+    using WixTestTools;
+    using Xunit;
+    using Xunit.Abstractions;
+
+    public class WixIuiBaTests : BurnE2ETests
+    {
+        public WixIuiBaTests(ITestOutputHelper testOutputHelper) : base(testOutputHelper) { }
+
+        [RuntimeFact]
+        public void CanInstallArchitectureSpecificPrimaryPackage()
+        {
+            var defaultPackage = this.CreatePackageInstaller("InternalUIPackage");
+            var x86Package = this.CreatePackageInstaller("InternalUIx86Package");
+            var x64Package = this.CreatePackageInstaller("InternalUIx64Package");
+            var arm64Package = this.CreatePackageInstaller("InternalUIarm64Package");
+            var bundle = this.CreateBundleInstaller("ArchSpecificBundle");
+
+            defaultPackage.VerifyInstalled(false);
+            x86Package.VerifyInstalled(false);
+            x64Package.VerifyInstalled(false);
+            arm64Package.VerifyInstalled(false);
+            bundle.VerifyUnregisteredAndRemovedFromPackageCache();
+
+            bundle.Install();
+            bundle.VerifyRegisteredAndInPackageCache();
+            defaultPackage.VerifyInstalled(false);
+
+            var archSpecificInstalls = 0;
+            if (x86Package.IsInstalled())
+            {
+                ++archSpecificInstalls;
+            }
+
+            if (x64Package.IsInstalled())
+            {
+                ++archSpecificInstalls;
+            }
+
+            if (arm64Package.IsInstalled())
+            {
+                ++archSpecificInstalls;
+            }
+
+            Assert.Equal(1, archSpecificInstalls);
+
+            bundle.Uninstall();
+            bundle.VerifyUnregisteredAndRemovedFromPackageCache();
+            defaultPackage.VerifyInstalled(false);
+            x86Package.VerifyInstalled(false);
+            x64Package.VerifyInstalled(false);
+            arm64Package.VerifyInstalled(false);
+        }
+
+        [RuntimeFact]
+        public void CanSilentlyInstallAndUninstallEmbeddedUIBundle()
+        {
+            var prereqPackage = this.CreatePackageInstaller("InternalUIPackage");
+            var package = this.CreatePackageInstaller("EmbeddedUIPackage");
+            var bundle = this.CreateBundleInstaller("EmbeddedUIBundle");
+
+            prereqPackage.VerifyInstalled(false);
+            package.VerifyInstalled(false);
+            bundle.VerifyUnregisteredAndRemovedFromPackageCache();
+
+            bundle.Install();
+            bundle.VerifyRegisteredAndInPackageCache();
+            prereqPackage.VerifyInstalled(true);
+            package.VerifyInstalled(true);
+
+            bundle.Uninstall();
+            bundle.VerifyUnregisteredAndRemovedFromPackageCache();
+            prereqPackage.VerifyInstalled(true);
+            package.VerifyInstalled(false);
+        }
+
+        [RuntimeFact]
+        public void CanSilentlyInstallAndUninstallInternalUIBundle()
+        {
+            var package = this.CreatePackageInstaller("InternalUIPackage");
+            var bundle = this.CreateBundleInstaller("InternalUIBundle");
+
+            package.VerifyInstalled(false);
+            bundle.VerifyUnregisteredAndRemovedFromPackageCache();
+
+            bundle.Install();
+            bundle.VerifyRegisteredAndInPackageCache();
+            package.VerifyInstalled(true);
+
+            bundle.Uninstall();
+            bundle.VerifyUnregisteredAndRemovedFromPackageCache();
+            package.VerifyInstalled(false);
+        }
+
+        // Manual test for EmbeddedUIBundle:
+        //  1. Double click EmbeddedUIBundle.exe.
+        //  2. Verify that the prereq BA came up and click the install button (allow elevation).
+        //  3. Verify that the prereq BA automatically closed after installing the prereq.
+        //  4. Verify that the MSI UI came up and click the install button.
+        //  5. After it's finished, click the exit button.
+        //  6. Verify that no other UI is shown and that everything was installed.
+        //  7. Double click EmbeddedUIBundle.exe (allow elevation).
+        //  8. Verify that the prereq BA did not come up.
+        //  9. Verify that the MSI UI came up and click the uninstall button.
+        // 10. After it's finished, click the exit button.
+        // 11. Verify that no other UI is shown and that everything was uninstalled except for the prereq which was permanent.
+        // 12. Uninstall InternalUIPackage to make sure the machine is clean for other tests.
+
+        // Alternate EmbeddedUIBundle test - manually install InternalUIPackage first and verify that the prereq BA doesn't come up during install either.
+
+        // Manual test for InternalUIBundle:
+        //  1. Double click InternalUIBundle.exe on a machine that will prompt for elevation.
+        //  2. Verify that the splash screen appeared but the prereq BA did not come up.
+        //  3. Verify that the elevation prompt came up immediately instead of flashing on the taskbar. (This is currently broken)
+        //  4. Allow elevation.
+        //  5. Verify that the MSI UI came up and the splash screen disappeared.
+        //  6. Accept the two CA messages and click the install button.
+        //  7. After it's finished, click the exit button.
+        //  8. Verify that no other UI is shown and that everything was installed.
+        //  9. Double click InternalUIBundle.exe (allow elevation).
+        // 10. Verify that the prereq BA did not come up.
+        // 11. Verify that the MSI UI came up and click the uninstall button.
+        // 12. After it's finished, click the exit button.
+        // 13. Verify that no other UI is shown and that everything was uninstalled to make sure the machine is clean for other tests.
+
+        // Manual test for Help:
+        // 1. Run EmbeddedUIBundle.exe /help from the command line.
+        // 2. Verify that the prereq BA shows the help information without trying to install the prereqs.
+
+        // Manual test for Layout:
+        // 1. Run EmbeddedUIBundle.exe /layout from an unelevated command line on a machine that will prompt for elevation.
+        // 2. Verify that the prereq BA performs the layout without requiring any input from the user.
+        // 3. Verify that it never prompted for elevation.
+        // 4. Click the exit button.
+
+        // Manual test for Caching error:
+        // 1. Copy InternalUIBundle.exe to a separate folder so that it can't find InternalUIPackage.msi.
+        // 2. Attempt to install InternalUIBundle.exe (allow elevation).
+        // 3. Verify that the prereq BA comes up with the Failure page saying that a file couldn't be found.
+    }
+}
diff --git a/src/test/dtf/Directory.Build.props b/src/test/dtf/Directory.Build.props
deleted file mode 100644
index 0035a9e6..00000000
--- a/src/test/dtf/Directory.Build.props
+++ /dev/null
@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
-<Project>
-  <PropertyGroup>
-    <SegmentName>IntegrationDtf</SegmentName>
-    <SignOutput>false</SignOutput>
-  </PropertyGroup>
-  
-  <Import Project="..\..\Directory.Build.props" />
-  <Import Project="Directory$(MSBuildProjectExtension).props" Condition=" Exists('Directory$(MSBuildProjectExtension).props') " />
-</Project>
diff --git a/src/test/dtf/Directory.Build.targets b/src/test/dtf/Directory.Build.targets
deleted file mode 100644
index 4e97b6ca..00000000
--- a/src/test/dtf/Directory.Build.targets
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
-<Project>
-  <Import Project="..\..\Directory.Build.targets" />
-  <Import Project="Directory$(MSBuildProjectExtension).targets" Condition=" Exists('Directory$(MSBuildProjectExtension).targets') " />
-</Project>
diff --git a/src/test/test.cmd b/src/test/test.cmd
index 1c2c154b..85deb61e 100644
--- a/src/test/test.cmd
+++ b/src/test/test.cmd
@@ -14,8 +14,6 @@
 @call msi\test_msi.cmd %_C% %_T% || exit /b
 @call burn\test_burn.cmd %_C% %_T% || exit /b
 
-msbuild -Restore dtf\DtfE2ETests.sln -p:Configuration=%_C% -nologo -m -warnaserror -bl:%_L%\dtfe2etests.binlog || exit /b
-
 dotnet test wix -c %_C% --nologo -l "trx;LogFileName=%_L%\TestResults\WixToolsetTest.WixE2ETests.trx" || exit /b
 
 @popd
diff --git a/src/wix/WixToolset.Core.Burn/Bind/GenerateManifestDataFromIRCommand.cs b/src/wix/WixToolset.Core.Burn/Bind/GenerateManifestDataFromIRCommand.cs
index 740a6e26..9eeafee3 100644
--- a/src/wix/WixToolset.Core.Burn/Bind/GenerateManifestDataFromIRCommand.cs
+++ b/src/wix/WixToolset.Core.Burn/Bind/GenerateManifestDataFromIRCommand.cs
@@ -10,6 +10,7 @@ namespace WixToolset.Core.Burn.Bind
     using WixToolset.Core.Burn.Bundles;
     using WixToolset.Core.Burn.ExtensibilityServices;
     using WixToolset.Data;
+    using WixToolset.Data.Burn;
     using WixToolset.Data.Symbols;
     using WixToolset.Extensibility;
     using WixToolset.Extensibility.Services;
@@ -191,10 +192,10 @@ namespace WixToolset.Core.Burn.Bind
                     switch (customDataSymbol.Type)
                     {
                         case WixBundleCustomDataType.BootstrapperApplication:
-                            writer.WriteStartElement(elementName, BurnCommon.BADataNamespace);
+                            writer.WriteStartElement(elementName, BurnConstants.BootstrapperApplicationDataNamespace);
                             break;
                         case WixBundleCustomDataType.BundleExtension:
-                            writer.WriteStartElement(elementName, BurnCommon.BundleExtensionDataNamespace);
+                            writer.WriteStartElement(elementName, BurnConstants.BundleExtensionDataNamespace);
                             break;
                         default:
                             throw new NotImplementedException();
diff --git a/src/wix/WixToolset.Core.Burn/Bundles/BurnCommon.cs b/src/wix/WixToolset.Core.Burn/Bundles/BurnCommon.cs
index 25ad88cf..08ed7d56 100644
--- a/src/wix/WixToolset.Core.Burn/Bundles/BurnCommon.cs
+++ b/src/wix/WixToolset.Core.Burn/Bundles/BurnCommon.cs
@@ -24,10 +24,8 @@ namespace WixToolset.Core.Burn.Bundles
         public const string BurnAuthoredContainerEmbeddedIdFormat = "a{0}";
 
         public const string BADataFileName = "BootstrapperApplicationData.xml";
-        public const string BADataNamespace = "http://wixtoolset.org/schemas/v4/BootstrapperApplicationData";
 
         public const string BundleExtensionDataFileName = "BundleExtensionData.xml";
-        public const string BundleExtensionDataNamespace = "http://wixtoolset.org/schemas/v4/BundleExtensionData";
 
         // See WinNT.h for details about the PE format, including the
         // structure and offsets for IMAGE_DOS_HEADER, IMAGE_NT_HEADERS32,
diff --git a/src/wix/WixToolset.Core.Burn/Bundles/CreateBootstrapperApplicationManifestCommand.cs b/src/wix/WixToolset.Core.Burn/Bundles/CreateBootstrapperApplicationManifestCommand.cs
index 3167ccd3..6d8e0822 100644
--- a/src/wix/WixToolset.Core.Burn/Bundles/CreateBootstrapperApplicationManifestCommand.cs
+++ b/src/wix/WixToolset.Core.Burn/Bundles/CreateBootstrapperApplicationManifestCommand.cs
@@ -67,7 +67,7 @@ namespace WixToolset.Core.Burn.Bundles
             {
                 writer.Formatting = Formatting.Indented;
                 writer.WriteStartDocument();
-                writer.WriteStartElement("BootstrapperApplicationData", BurnCommon.BADataNamespace);
+                writer.WriteStartElement("BootstrapperApplicationData", BurnConstants.BootstrapperApplicationDataNamespace);
 
                 this.WriteBundleInfo(writer);
 
diff --git a/src/wix/WixToolset.Core.Burn/Bundles/CreateBundleExtensionManifestCommand.cs b/src/wix/WixToolset.Core.Burn/Bundles/CreateBundleExtensionManifestCommand.cs
index e587413e..ab6dcea1 100644
--- a/src/wix/WixToolset.Core.Burn/Bundles/CreateBundleExtensionManifestCommand.cs
+++ b/src/wix/WixToolset.Core.Burn/Bundles/CreateBundleExtensionManifestCommand.cs
@@ -53,7 +53,7 @@ namespace WixToolset.Core.Burn.Bundles
             {
                 writer.Formatting = Formatting.Indented;
                 writer.WriteStartDocument();
-                writer.WriteStartElement("BundleExtensionData", BurnCommon.BundleExtensionDataNamespace);
+                writer.WriteStartElement("BundleExtensionData", BurnConstants.BundleExtensionDataNamespace);
 
                 this.InternalBurnBackendHelper.WriteBundleExtensionData(writer);
 
diff --git a/src/wix/WixToolset.Core.Burn/ExtensibilityServices/BurnBackendHelper.cs b/src/wix/WixToolset.Core.Burn/ExtensibilityServices/BurnBackendHelper.cs
index 52f01f58..e267369f 100644
--- a/src/wix/WixToolset.Core.Burn/ExtensibilityServices/BurnBackendHelper.cs
+++ b/src/wix/WixToolset.Core.Burn/ExtensibilityServices/BurnBackendHelper.cs
@@ -9,6 +9,7 @@ namespace WixToolset.Core.Burn.ExtensibilityServices
     using System.Xml;
     using WixToolset.Core.Burn.Bundles;
     using WixToolset.Data;
+    using WixToolset.Data.Burn;
     using WixToolset.Data.Symbols;
     using WixToolset.Data.WindowsInstaller.Rows;
     using WixToolset.Extensibility.Data;
@@ -160,7 +161,7 @@ namespace WixToolset.Core.Burn.ExtensibilityServices
 
         public void AddBootstrapperApplicationData(IntermediateSymbol symbol, bool symbolIdIsIdAttribute = false)
         {
-            this.BootstrapperApplicationManifestData.AddSymbol(symbol, symbolIdIsIdAttribute, BurnCommon.BADataNamespace);
+            this.BootstrapperApplicationManifestData.AddSymbol(symbol, symbolIdIsIdAttribute, BurnConstants.BootstrapperApplicationDataNamespace);
         }
 
         public void AddBundleExtensionData(string extensionId, string xml)
@@ -172,7 +173,7 @@ namespace WixToolset.Core.Burn.ExtensibilityServices
         public void AddBundleExtensionData(string extensionId, IntermediateSymbol symbol, bool symbolIdIsIdAttribute = false)
         {
             var manifestData = this.GetBundleExtensionManifestData(extensionId);
-            manifestData.AddSymbol(symbol, symbolIdIsIdAttribute, BurnCommon.BundleExtensionDataNamespace);
+            manifestData.AddSymbol(symbol, symbolIdIsIdAttribute, BurnConstants.BundleExtensionDataNamespace);
         }
 
         #endregion
diff --git a/src/wix/WixToolset.Core.TestPackage/BundleExtractor.cs b/src/wix/WixToolset.Core.TestPackage/BundleExtractor.cs
index bd13a9b2..3cc98e3a 100644
--- a/src/wix/WixToolset.Core.TestPackage/BundleExtractor.cs
+++ b/src/wix/WixToolset.Core.TestPackage/BundleExtractor.cs
@@ -5,6 +5,7 @@ namespace WixToolset.Core.TestPackage
     using System.IO;
     using System.Xml;
     using WixToolset.Core.Burn.Bundles;
+    using WixToolset.Data.Burn;
     using WixToolset.Extensibility.Services;
 
     /// <summary>
@@ -72,7 +73,7 @@ namespace WixToolset.Core.TestPackage
         public static XmlNamespaceManager GetBADataNamespaceManager(XmlDocument document, string prefix)
         {
             var namespaceManager = new XmlNamespaceManager(document.NameTable);
-            namespaceManager.AddNamespace(prefix, BurnCommon.BADataNamespace);
+            namespaceManager.AddNamespace(prefix, BurnConstants.BootstrapperApplicationDataNamespace);
             return namespaceManager;
         }
 
@@ -85,7 +86,7 @@ namespace WixToolset.Core.TestPackage
         public static XmlNamespaceManager GetBundleExtensionDataNamespaceManager(XmlDocument document, string prefix)
         {
             var namespaceManager = new XmlNamespaceManager(document.NameTable);
-            namespaceManager.AddNamespace(prefix, BurnCommon.BundleExtensionDataNamespace);
+            namespaceManager.AddNamespace(prefix, BurnConstants.BundleExtensionDataNamespace);
             return namespaceManager;
         }