diff --git a/src/SourceBuild/content/build.proj b/src/SourceBuild/content/build.proj
index bbcfd977b..65f27db57 100644
--- a/src/SourceBuild/content/build.proj
+++ b/src/SourceBuild/content/build.proj
@@ -1,11 +1,32 @@
-<Project Sdk="Microsoft.Build.Traversal">
+<Project Sdk="Microsoft.Build.Traversal" InitialTargets="PrintInfo">
+
+<!-- Default targets and parallelization -->
+ <ItemDefinitionGroup>
+    <ProjectReference>
+      <Test>false</Test>
+      <Publish>false</Publish>
+      <BuildInParallel>false</BuildInParallel>
+    </ProjectReference>
+  </ItemDefinitionGroup>
 
   <ItemGroup>
-    <ProjectReference Include="$(ToolsDir)init-build.proj" BuildInParallel="false" />
-    <ProjectReference Include="$(RepoProjectsDir)$(RootRepo).proj" BuildInParallel="false" />
+    <!-- Pre-build: Init tools-->
+    <ProjectReference Include="$(RepositoryEngineeringDir)init-cross-build.proj"
+                      Condition="'$(BuildOS)' != 'windows' and '$(CrossBuild)' == 'true' and '$(ROOTFS_DIR)' == ''"
+                      BuildInParallel="true" />
+    <ProjectReference Include="$(RepositoryEngineeringDir)init-poison.proj"
+                      Condition="'$(EnablePoison)' == 'true'"
+                      BuildInParallel="true" />
+    <ProjectReference Include="$(ToolsDir)tools.proj" BuildInParallel="true" />
+
+    <ProjectReference Include="$(RepoProjectsDir)$(RootRepo).proj" />
+
+    <!-- Post-build: Source-only validation, packaging and publishing -->
+    <ProjectReference Include="$(RepositoryEngineeringDir)finish-source-only.proj" Condition="'$(DotNetBuildSourceOnly)' == 'true'" />
+    <ProjectReference Include="$(RepositoryEngineeringDir)publish.proj" />
   </ItemGroup>
 
-  <Target Name="PrintInfo" BeforeTargets="Build">
+  <Target Name="PrintInfo">
     <PropertyGroup>
       <BuildModeInfoText Condition="'$(DotNetBuildSourceOnly)' == 'true'">source-build</BuildModeInfoText>
       <BuildModeInfoText Condition="'$(DotNetBuildSourceOnly)' != 'true'">non-source-build</BuildModeInfoText>
@@ -15,27 +36,6 @@
     <Message Text="Build Environment: $(TargetArchitecture) $(Configuration) $(TargetOS) $(TargetRid)" Importance="high" />
   </Target>
 
-  <!-- Create a merge manifest from the individual repository manifest files. -->
-  <UsingTask TaskName="Microsoft.DotNet.UnifiedBuild.Tasks.MergeAssetManifests" AssemblyFile="$(MicrosoftDotNetUnifiedBuildTasksAssembly)" TaskFactory="TaskHostFactory" />
-  <Target Name="MergeAssetManifests" AfterTargets="Build">
-    <PropertyGroup>
-      <MergedAssetManifestOutputPath>$(ArtifactsDir)VerticalManifest.xml</MergedAssetManifestOutputPath>
-    </PropertyGroup>
-
-    <ItemGroup>
-      <RepoAssetManifest Include="$(AssetManifestsIntermediateDir)\**\*.xml" />
-    </ItemGroup>
-
-    <!-- It's OK for the VmrBuildNumber to be empty -->
-    <Microsoft.DotNet.UnifiedBuild.Tasks.MergeAssetManifests 
-      AssetManifest="@(RepoAssetManifest)" 
-      MergedAssetManifestOutputPath="$(MergedAssetManifestOutputPath)"
-      VmrBuildNumber="$(BUILD_BUILDNUMBER)" />
-  </Target>
-
-  <Import Project="$(RepositoryEngineeringDir)build.sourcebuild.targets" Condition="'$(DotNetBuildSourceOnly)' == 'true'" />
-
-  <!-- Intentionally below the import to appear at the end. -->
   <Target Name="LogBuildOutputFolders"
           AfterTargets="Build">
     <Message Importance="high" Text="Shipping packages are located in '$(ArtifactsShippingPackagesDir)'." />
diff --git a/src/SourceBuild/content/build.sh b/src/SourceBuild/content/build.sh
index 91555c833..706d131d2 100755
--- a/src/SourceBuild/content/build.sh
+++ b/src/SourceBuild/content/build.sh
@@ -234,7 +234,7 @@ function Build {
 
     if [ "$test" != "true" ]; then
       "$CLI_ROOT/dotnet" build-server shutdown
-      "$CLI_ROOT/dotnet" msbuild "$scriptroot/eng/tools/init-build.proj" -bl:"$scriptroot/artifacts/log/$configuration/BuildMSBuildSdkResolver.binlog" -flp:LogFile="$scriptroot/artifacts/log/$configuration/BuildMSBuildSdkResolver.log" /t:ExtractToolsetPackages,BuildMSBuildSdkResolver $properties
+      "$CLI_ROOT/dotnet" msbuild "$scriptroot/eng/init-source-only.proj" -bl:"$scriptroot/artifacts/log/$configuration/BuildMSBuildSdkResolver.binlog" $properties
       # kill off the MSBuild server so that on future invocations we pick up our custom SDK Resolver
       "$CLI_ROOT/dotnet" build-server shutdown
     fi
diff --git a/src/SourceBuild/content/eng/detect-binaries.sh b/src/SourceBuild/content/eng/detect-binaries.sh
index 59c78dd71..f43c708f0 100755
--- a/src/SourceBuild/content/eng/detect-binaries.sh
+++ b/src/SourceBuild/content/eng/detect-binaries.sh
@@ -36,6 +36,7 @@ mode='validate'
 logLevel='Debug'
 propsDir=''
 packagesDir=''
+restoreSources=''
 dotnetSdk=$defaultDotnetSdk
 
 positional_args=()
@@ -114,10 +115,9 @@ function ParseBinaryArgs
     # Check the packages directory
     if [ -z "$packagesDir" ]; then
         # Use dotnet-public and dotnet-libraries feeds as the default packages source feeds
-        export ARTIFACTS_PATH="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json;https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-libraries/nuget/v3/index.json"
+        restoreSources="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json%3Bhttps://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-libraries/nuget/v3/index.json"
     else
-        packagesDir=$(realpath ${packagesDir})
-        export ARTIFACTS_PATH=$packagesDir
+        restoreSources=$(realpath ${packagesDir})
     fi
 }
 
@@ -125,7 +125,7 @@ function RunBinaryTool
 {
   targetDir="$REPO_ROOT"
   outputDir="$REPO_ROOT/artifacts/log/binary-report"
-  BinaryToolCommand=""$dotnetSdk/dotnet" run --project "$BINARY_TOOL" -c Release "$mode" "$targetDir" -o "$outputDir" -ab "$allowedBinariesFile" -l "$logLevel""
+  BinaryToolCommand=""$dotnetSdk/dotnet" run --project "$BINARY_TOOL" -c Release --property:RestoreSources="$restoreSources" "$mode" "$targetDir" -o "$outputDir" -ab "$allowedBinariesFile" -l "$logLevel""
 
   if [ -n "$packagesDir" ]; then
     BinaryToolCommand=""$BinaryToolCommand" -p CustomPackageVersionsProps="$packagesDir/PackageVersions.props""
@@ -136,4 +136,4 @@ function RunBinaryTool
 }
 
 ParseBinaryArgs
-RunBinaryTool
\ No newline at end of file
+RunBinaryTool
diff --git a/src/SourceBuild/content/eng/build.sourcebuild.targets b/src/SourceBuild/content/eng/finish-source-only.proj
similarity index 93%
rename from src/SourceBuild/content/eng/build.sourcebuild.targets
rename to src/SourceBuild/content/eng/finish-source-only.proj
index ca13c113a..bdbfeebaf 100644
--- a/src/SourceBuild/content/eng/build.sourcebuild.targets
+++ b/src/SourceBuild/content/eng/finish-source-only.proj
@@ -1,4 +1,14 @@
-<Project>
+
+<Project Sdk="Microsoft.Build.NoTargets">
+
+  <PropertyGroup>
+    <TargetFramework>$(NetCurrent)</TargetFramework>
+  </PropertyGroup>
+  
+  <ItemGroup>
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.UnifiedBuild.Tasks\Microsoft.DotNet.UnifiedBuild.Tasks.csproj" />
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.SourceBuild.Tasks.LeakDetection\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.csproj" />
+  </ItemGroup>
 
   <!-- After building, generate a prebuilt usage report. -->
   <Target Name="ReportPrebuiltUsage"
@@ -145,7 +155,7 @@
 
   <Target Name="CreatePrebuiltsTarballIfPrebuiltsExist"
           DependsOnTargets="DetermineSourceBuiltSdkVersion"
-          Condition="'@(PrebuiltFile->Count())' != '0'">
+          Condition="'@(PrebuiltFile)' != ''">
     <PropertyGroup>
       <PrebuiltsTarball>$(ArtifactsAssetsDir)$(SourceBuiltPrebuiltsTarballName).$(SourceBuiltSdkVersion).$(TargetRid)$(ArchiveExtension)</PrebuiltsTarball>
       <PrebuiltsTarballWorkingDir>$(ResultingPrebuiltPackagesDir)</PrebuiltsTarballWorkingDir>
@@ -158,7 +168,7 @@
   </Target>
 
   <Target Name="ErrorOnPrebuilts"
-          Condition="'@(PrebuiltFile->Count())' != '0' AND '$(SkipErrorOnPrebuilts)' != 'true'">
+          Condition="'@(PrebuiltFile)' != '' and '$(SkipErrorOnPrebuilts)' != 'true'">
     <Error Text="@(PrebuiltFile->Count()) Prebuilts Exist" />
   </Target>
 
diff --git a/src/SourceBuild/content/eng/init-cross-build.proj b/src/SourceBuild/content/eng/init-cross-build.proj
new file mode 100644
index 000000000..f017ae51d
--- /dev/null
+++ b/src/SourceBuild/content/eng/init-cross-build.proj
@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.Build.NoTargets">
+
+  <PropertyGroup>
+    <TargetFramework>$(NetCurrent)</TargetFramework>
+  </PropertyGroup>
+
+  <Target Name="GenerateRootFs"
+          AfterTargets="Build">
+    <PropertyGroup>
+      <ArmEnvironmentVariables Condition="'$(ArmEnvironmentVariables)' == ''">ROOTFS_DIR=$(ArtifactsObjDir)crossrootfs/arm</ArmEnvironmentVariables>
+      <ArmEnvironmentVariables Condition="'$(Platform)' == 'armel'">ROOTFS_DIR=$(ArtifactsObjDir)crossrootfs/armel</ArmEnvironmentVariables>
+    </PropertyGroup>
+
+    <Exec Command="$(RepositoryEngineeringDir)common/cross/build-rootfs.sh"
+          EnvironmentVariables="$(ArmEnvironmentVariables)"
+          Condition="'$(TargetArchitecture)' != 'armel' and '$(BuildArchitecture)' != '$(TargetArchitecture)'" />
+    <Exec Command="$(RepositoryEngineeringDir)common/cross/armel/tizen-build-rootfs.sh"
+          EnvironmentVariables="$(ArmEnvironmentVariables)"
+          Condition="'$(TargetArchitecture)' == 'armel'" />
+  </Target>
+
+</Project>
diff --git a/src/SourceBuild/content/eng/init-poison.proj b/src/SourceBuild/content/eng/init-poison.proj
new file mode 100644
index 000000000..d1497ccd9
--- /dev/null
+++ b/src/SourceBuild/content/eng/init-poison.proj
@@ -0,0 +1,39 @@
+<Project Sdk="Microsoft.Build.NoTargets">
+
+  <PropertyGroup>
+    <TargetFramework>$(NetCurrent)</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.SourceBuild.Tasks.LeakDetection\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.csproj" />
+  </ItemGroup>
+
+  <UsingTask TaskName="Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.MarkAndCatalogPackages" AssemblyFile="$(MicrosoftDotNetSourceBuildTasksLeakDetectionAssembly)" TaskFactory="TaskHostFactory" />
+  <Target Name="PoisonPrebuiltPackages"
+          AfterTargets="Build"
+          Inputs="$(MSBuildProjectFullPath)"
+          Outputs="$(BaseIntermediateOutputPath)PoisonPrebuiltPackages.complete">
+    <PropertyGroup>
+      <SourceBuiltPoisonMarkerFile>.source-built.xml</SourceBuiltPoisonMarkerFile>
+      <SourceBuiltPoisonReportDataFile>$(PackageReportDir)poison-source-built-catalog.xml</SourceBuiltPoisonReportDataFile>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <PrebuiltPackages Include="$(PrebuiltPackagesPath)**/*.nupkg" />
+      <PrebuiltSourceBuiltPackages Include="$(PrebuiltSourceBuiltPackagesPath)**/*.nupkg" />
+    </ItemGroup>
+
+    <Message Importance="High" Text="[$([System.DateTime]::Now.ToString('HH:mm:ss.ff'))] Poisoning existing packages for leak detection." />
+
+    <MarkAndCatalogPackages PackagesToMark="@(PrebuiltPackages)" CatalogOutputFilePath="$(PoisonReportDataFile)" MarkerFileName="$(PoisonMarkerFile)" />
+    <MarkAndCatalogPackages PackagesToMark="@(PrebuiltSourceBuiltPackages)" CatalogOutputFilePath="$(SourceBuiltPoisonReportDataFile)" MarkerFileName="$(SourceBuiltPoisonMarkerFile)" />
+
+    <Message Importance="High" Text="[$([System.DateTime]::Now.ToString('HH:mm:ss.ff'))] Done poisoning." />
+
+    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
+    <Touch Files="$(BaseIntermediateOutputPath)PoisonPrebuiltPackages.complete" AlwaysCreate="true">
+      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
+    </Touch>
+  </Target>
+
+</Project>
diff --git a/src/SourceBuild/content/eng/init-source-only.proj b/src/SourceBuild/content/eng/init-source-only.proj
new file mode 100644
index 000000000..f45d4a70c
--- /dev/null
+++ b/src/SourceBuild/content/eng/init-source-only.proj
@@ -0,0 +1,97 @@
+<Project>
+
+  <!-- This project must not use any prebuilts -->
+
+  <PropertyGroup>
+    <SkipArcadeSdkImport>true</SkipArcadeSdkImport>
+    <!-- Fake, to satisfy the SDK. -->
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <DisableImplicitFrameworkReferences>true</DisableImplicitFrameworkReferences>
+    <EnableDefaultItems>false</EnableDefaultItems>
+  </PropertyGroup>
+
+  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk" />
+  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
+
+  <Target Name="Build"
+          DependsOnTargets="
+      UnpackTarballs;
+      BuildMSBuildSdkResolver;
+      ExtractToolsetPackages" />
+
+  <Target Name="UnpackTarballs"
+          Inputs="$(MSBuildProjectFullPath)"
+          Outputs="$(BaseIntermediateOutputPath)UnpackTarballs.complete" >
+    <PropertyGroup>
+      <ExternalTarballsDir>$([MSBuild]::NormalizeDirectory('$(PrereqsPackagesDir)', 'archive'))</ExternalTarballsDir>
+    </PropertyGroup>
+
+    <MakeDir Directories="$(PrebuiltSourceBuiltPackagesPath)" Condition="'$(CustomPrebuiltSourceBuiltPackagesPath)' == ''" />
+    <Exec Command="tar -xzf $(ExternalTarballsDir)$(SourceBuiltArtifactsTarballName).*$(ArchiveExtension)"
+          WorkingDirectory="$(PrebuiltSourceBuiltPackagesPath)"
+          Condition="'$(CustomPrebuiltSourceBuiltPackagesPath)' == ''" />
+
+    <!--
+      Check for a prebuilt dependency tarball and extract if exists. If there isn't one, we expect
+      the build to be working without prebuilts.
+    -->
+    <ItemGroup>
+      <SourceBuiltPrebuiltsTarballFile Include="$(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*$(ArchiveExtension)" />
+    </ItemGroup>
+    <Exec Command="tar -xzf %(SourceBuiltPrebuiltsTarballFile.FullPath)"
+          WorkingDirectory="$(PrebuiltPackagesPath)"
+          Condition="'@(SourceBuiltPrebuiltsTarballFile)' != ''" />
+
+    <!-- Copy SBRP packages to reference packages location -->
+    <ItemGroup>
+      <UnpackedSourceBuildReferencePackages Include="$(PrebuiltSourceBuiltPackagesPath)SourceBuildReferencePackages/*"/>
+    </ItemGroup>
+
+    <Move SourceFiles="@(UnpackedSourceBuildReferencePackages)" DestinationFiles="$(ReferencePackagesDir)%(Filename)%(Extension)" />
+
+    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
+    <Touch Files="$(BaseIntermediateOutputPath)UnpackTarballs.complete" AlwaysCreate="true">
+      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
+    </Touch>
+  </Target>
+
+  <!-- Build the custom msbuild sdk resolver. -->
+  <Target Name="BuildMSBuildSdkResolver"
+          DependsOnTargets="UnpackTarballs"
+          Inputs="$(MSBuildProjectFullPath)"
+          Outputs="$(BaseIntermediateOutputPath)BuildMSBuildSdkResolver.complete">
+    <MSBuild Projects="$(TasksDir)Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj"
+             Targets="Restore"
+             Properties="MSBuildRestoreSessionId=$([System.Guid]::NewGuid())" />
+
+    <MSBuild Projects="$(TasksDir)Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj"
+             Targets="Build" />
+
+    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
+    <Touch Files="$(BaseIntermediateOutputPath)BuildMSBuildSdkResolver.complete" AlwaysCreate="true">
+      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
+    </Touch>
+  </Target>
+
+  <!-- Extract toolset packages into the bootstrap folder -->
+  <Target Name="ExtractToolsetPackages"
+          DependsOnTargets="UnpackTarballs"
+          Inputs="$(MSBuildProjectFullPath)"
+          Outputs="$(BaseIntermediateOutputPath)ExtractToolsetPackages.complete">
+    <ItemGroup>
+      <ToolsetPackage Include="Microsoft.DotNet.Arcade.Sdk" SourceFolder="$(PrebuiltSourceBuiltPackagesPath)" Version="$(ARCADE_BOOTSTRAP_VERSION)" />
+      <ToolsetPackage Include="Microsoft.Build.NoTargets" SourceFolder="$(ReferencePackagesDir)" Version="$(NOTARGETS_BOOTSTRAP_VERSION)" />
+      <ToolsetPackage Include="Microsoft.Build.Traversal" SourceFolder="$(ReferencePackagesDir)" Version="$(TRAVERSAL_BOOTSTRAP_VERSION)" />
+    </ItemGroup>
+
+    <Unzip SourceFiles="%(ToolsetPackage.SourceFolder)%(ToolsetPackage.Identity).%(ToolsetPackage.Version).nupkg"
+           DestinationFolder="$(BootstrapPackagesDir)$([System.String]::Copy('%(ToolsetPackage.Identity)').ToLowerInvariant())/%(ToolsetPackage.Version)"
+           SkipUnchangedFiles="true" />
+
+    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
+    <Touch Files="$(BaseIntermediateOutputPath)ExtractToolsetPackages.complete" AlwaysCreate="true">
+      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
+    </Touch>
+  </Target>
+
+</Project>
diff --git a/src/SourceBuild/content/eng/publish.proj b/src/SourceBuild/content/eng/publish.proj
new file mode 100644
index 000000000..05355e66f
--- /dev/null
+++ b/src/SourceBuild/content/eng/publish.proj
@@ -0,0 +1,29 @@
+<Project Sdk="Microsoft.Build.NoTargets">
+
+  <PropertyGroup>
+    <TargetFramework>$(NetCurrent)</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.UnifiedBuild.Tasks\Microsoft.DotNet.UnifiedBuild.Tasks.csproj" />
+  </ItemGroup>
+
+  <!-- Create a merge manifest from the individual repository manifest files. -->
+  <UsingTask TaskName="Microsoft.DotNet.UnifiedBuild.Tasks.MergeAssetManifests" AssemblyFile="$(MicrosoftDotNetUnifiedBuildTasksAssembly)" TaskFactory="TaskHostFactory" />
+  <Target Name="MergeAssetManifests" AfterTargets="Build">
+    <PropertyGroup>
+      <MergedAssetManifestOutputPath>$(ArtifactsDir)VerticalManifest.xml</MergedAssetManifestOutputPath>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <RepoAssetManifest Include="$(AssetManifestsIntermediateDir)\**\*.xml" />
+    </ItemGroup>
+
+    <!-- It's OK for the VmrBuildNumber to be empty -->
+    <Microsoft.DotNet.UnifiedBuild.Tasks.MergeAssetManifests 
+      AssetManifest="@(RepoAssetManifest)" 
+      MergedAssetManifestOutputPath="$(MergedAssetManifestOutputPath)"
+      VmrBuildNumber="$(BUILD_BUILDNUMBER)" />
+  </Target>
+
+</Project>
\ No newline at end of file
diff --git a/src/SourceBuild/content/eng/tools/BinaryToolKit/Directory.Build.props b/src/SourceBuild/content/eng/tools/BinaryToolKit/Directory.Build.props
new file mode 100644
index 000000000..560e3a358
--- /dev/null
+++ b/src/SourceBuild/content/eng/tools/BinaryToolKit/Directory.Build.props
@@ -0,0 +1,13 @@
+<Project>
+
+  <!--
+    Do not import the Arcade SDK as this would introduce a prebuilt as this project builds
+    before the custom sdk resolver is available in source-only mode.
+  -->
+  <PropertyGroup>
+    <SkipArcadeSdkImport>true</SkipArcadeSdkImport>
+  </PropertyGroup>
+
+  <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props, $(MSBuildThisFileDirectory)..))" />
+
+</Project>
diff --git a/src/SourceBuild/content/eng/tools/BinaryToolKit/NuGet.config b/src/SourceBuild/content/eng/tools/BinaryToolKit/NuGet.config
deleted file mode 100644
index 9d4d1db97..000000000
--- a/src/SourceBuild/content/eng/tools/BinaryToolKit/NuGet.config
+++ /dev/null
@@ -1,7 +0,0 @@
-<configuration>
-  <packageSources>
-    <clear />
-    <!-- %ARTIFACTS_PATH% must be set via an environment variable (export ARTIFACTS_PATH=<path-to-sources>). -->
-    <add key="artifactsPath" value="%ARTIFACTS_PATH%" />
-  </packageSources>
-</configuration>
diff --git a/src/SourceBuild/content/eng/tools/Directory.Build.props b/src/SourceBuild/content/eng/tools/Directory.Build.props
index 63c892c31..7c1442273 100644
--- a/src/SourceBuild/content/eng/tools/Directory.Build.props
+++ b/src/SourceBuild/content/eng/tools/Directory.Build.props
@@ -1,13 +1,21 @@
 <Project>
 
-  <!--
-    Do not import the Arcade SDK for the local tooling projects. This lets us
-    build them with just the .NET SDK, simplifying the build.
-  -->
-  <PropertyGroup>
-    <SkipArcadeSdkImport>true</SkipArcadeSdkImport>
-  </PropertyGroup>
-
   <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props, $(MSBuildThisFileDirectory)..))" />
 
+  <PropertyGroup>
+    <RestoreSources Condition="'$(DotNetBuildSourceOnly)' == 'true'">$(ReferencePackagesDir);$(PrebuiltPackagesPath);$(PrebuiltSourceBuiltPackagesPath)</RestoreSources>
+  </PropertyGroup>
+
+  <!--
+    Use some assemblies from the SDK, instead of package references. This ensures they match what's
+    found when the task is loaded by the SDK's MSBuild.
+    Reference NuGet assemblies, except a command line assembly that causes warnings such as:
+    MSB3277: Found conflicts between different versions of "System.Collections" that could not be resolved.
+  -->
+  <ItemGroup>
+    <SdkAssembly Include="$([MSBuild]::NormalizePath('$(NetCoreRoot)', 'sdk', '$(NETCoreSdkVersion)', 'Newtonsoft.Json.dll'));
+                          $([MSBuild]::NormalizeDirectory('$(NetCoreRoot)', 'sdk', '$(NETCoreSdkVersion)'))NuGet.*.dll"
+                 Exclude="$([MSBuild]::NormalizePath('$(NetCoreRoot)', 'sdk', '$(NETCoreSdkVersion)', 'NuGet.CommandLine.XPlat.dll'))" />
+  </ItemGroup>
+
 </Project>
diff --git a/src/SourceBuild/content/eng/tools/init-build.proj b/src/SourceBuild/content/eng/tools/init-build.proj
deleted file mode 100644
index 7dece577b..000000000
--- a/src/SourceBuild/content/eng/tools/init-build.proj
+++ /dev/null
@@ -1,179 +0,0 @@
-<Project>
-
-  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk" />
-
-  <PropertyGroup>
-    <!-- Fake, to satisfy the SDK. -->
-    <TargetFramework>netstandard2.0</TargetFramework>
-    <DisableImplicitFrameworkReferences>true</DisableImplicitFrameworkReferences>
-    <EnableDefaultItems>false</EnableDefaultItems>
-  </PropertyGroup>
-
-  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
-
-  <Target Name="Build"
-          DependsOnTargets="
-      UnpackTarballs;
-      BuildUnifiedBuildTasks;
-      BuildMSBuildSdkResolver;
-      BuildLeakDetection;
-      ExtractToolsetPackages;
-      GenerateRootFs;
-      PoisonPrebuiltPackages" />
-
-  <Target Name="UnpackTarballs"
-          Condition="'$(DotNetBuildSourceOnly)' == 'true'"
-          Inputs="$(MSBuildProjectFullPath)"
-          Outputs="$(BaseIntermediateOutputPath)UnpackTarballs.complete" >
-    <PropertyGroup>
-      <ExternalTarballsDir>$([MSBuild]::NormalizeDirectory('$(PrereqsPackagesDir)', 'archive'))</ExternalTarballsDir>
-    </PropertyGroup>
-
-    <MakeDir Directories="$(PrebuiltSourceBuiltPackagesPath)" Condition="'$(CustomPrebuiltSourceBuiltPackagesPath)' == ''" />
-    <Exec Command="tar -xzf $(ExternalTarballsDir)$(SourceBuiltArtifactsTarballName).*$(ArchiveExtension)"
-          WorkingDirectory="$(PrebuiltSourceBuiltPackagesPath)"
-          Condition="'$(CustomPrebuiltSourceBuiltPackagesPath)' == ''" />
-
-    <!--
-      Check for a prebuilt dependency tarball and extract if exists. If there isn't one, we expect
-      the build to be working without prebuilts.
-    -->
-    <ItemGroup>
-      <SourceBuiltPrebuiltsTarballFile Include="$(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*$(ArchiveExtension)" />
-    </ItemGroup>
-    <Exec Command="tar -xzf %(SourceBuiltPrebuiltsTarballFile.FullPath)"
-          WorkingDirectory="$(PrebuiltPackagesPath)"
-          Condition="'@(SourceBuiltPrebuiltsTarballFile)' != ''" />
-
-    <!-- Copy SBRP packages to reference packages location -->
-    <ItemGroup>
-      <UnpackedSourceBuildReferencePackages Include="$(PrebuiltSourceBuiltPackagesPath)SourceBuildReferencePackages/*"/>
-    </ItemGroup>
-
-    <Move SourceFiles="@(UnpackedSourceBuildReferencePackages)" DestinationFiles="$(ReferencePackagesDir)%(Filename)%(Extension)" />
-
-    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
-    <Touch Files="$(BaseIntermediateOutputPath)UnpackTarballs.complete" AlwaysCreate="true">
-      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
-    </Touch>
-  </Target>
-
-  <!-- Build the custom msbuild sdk resolver. -->
-  <Target Name="BuildMSBuildSdkResolver"
-          DependsOnTargets="UnpackTarballs"
-          Inputs="$(MSBuildProjectFullPath)"
-          Outputs="$(BaseIntermediateOutputPath)BuildMSBuildSdkResolver.complete">
-    <MSBuild Projects="tasks\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj"
-             Targets="Restore"
-             Properties="MSBuildRestoreSessionId=$([System.Guid]::NewGuid())" />
-
-    <MSBuild Projects="tasks\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj"
-             Targets="Build" />
-
-    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
-    <Touch Files="$(BaseIntermediateOutputPath)BuildMSBuildSdkResolver.complete" AlwaysCreate="true">
-      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
-    </Touch>
-  </Target>
-
-  <!-- Build msbuild tasks. -->
-  <Target Name="BuildUnifiedBuildTasks"
-          DependsOnTargets="UnpackTarballs;BuildMSBuildSdkResolver"
-          Inputs="$(MSBuildProjectFullPath)"
-          Outputs="$(BaseIntermediateOutputPath)BuildUnifiedBuildTasks.complete">
-    <MSBuild Projects="tasks\Microsoft.DotNet.UnifiedBuild.Tasks\Microsoft.DotNet.UnifiedBuild.Tasks.csproj"
-             Targets="Restore"
-             Properties="MSBuildRestoreSessionId=$([System.Guid]::NewGuid())" />
-
-    <MSBuild Projects="tasks\Microsoft.DotNet.UnifiedBuild.Tasks\Microsoft.DotNet.UnifiedBuild.Tasks.csproj"
-             Targets="Build" />
-
-    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
-    <Touch Files="$(BaseIntermediateOutputPath)BuildUnifiedBuildTasks.complete" AlwaysCreate="true">
-      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
-    </Touch>
-  </Target>
-
-  <!-- Build msbuild tasks for the poisoning feature even when EnablePoison!=true to validate that the task project
-       builds as EnablePoison=true isn't exercised in PR validation. -->
-  <Target Name="BuildLeakDetection"
-          DependsOnTargets="ExtractToolsetPackages;BuildMSBuildSdkResolver"
-          Inputs="$(MSBuildProjectFullPath)"
-          Outputs="$(BaseIntermediateOutputPath)BuildLeakDetection.complete">
-    <MSBuild Projects="tasks\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.csproj"
-             Targets="Restore"
-             Properties="MSBuildRestoreSessionId=$([System.Guid]::NewGuid())" />
-
-    <MSBuild Projects="tasks\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.csproj"
-             Targets="Build" />
-
-    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
-    <Touch Files="$(BaseIntermediateOutputPath)BuildLeakDetection.complete" AlwaysCreate="true">
-      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
-    </Touch>
-  </Target>
-
-  <Target Name="GenerateRootFs"
-          Condition="'$(BuildOS)' != 'windows' and '$(CrossBuild)' == 'true' and '$(ROOTFS_DIR)' == ''">
-    <PropertyGroup>
-      <ArmEnvironmentVariables Condition="'$(ArmEnvironmentVariables)' == ''">ROOTFS_DIR=$(ArtifactsObjDir)crossrootfs/arm</ArmEnvironmentVariables>
-      <ArmEnvironmentVariables Condition="'$(Platform)' == 'armel'">ROOTFS_DIR=$(ArtifactsObjDir)crossrootfs/armel</ArmEnvironmentVariables>
-    </PropertyGroup>
-
-    <Exec Command="$(ArmEnvironmentVariables) $(RepositoryEngineeringDir)common/cross/build-rootfs.sh"
-          Condition="'$(TargetArchitecture)' != 'armel' and '$(BuildArchitecture)' != '$(TargetArchitecture)'" />
-    <Exec Command="$(ArmEnvironmentVariables) $(RepositoryEngineeringDir)common/cross/armel/tizen-build-rootfs.sh"
-          Condition="'$(TargetArchitecture)' == 'armel'" />
-  </Target>
-
-  <!-- Extract toolset packages into the bootstrap folder -->
-  <Target Name="ExtractToolsetPackages"
-          Condition="'$(DotNetBuildSourceOnly)' == 'true'"
-          DependsOnTargets="UnpackTarballs"
-          Inputs="$(MSBuildProjectFullPath)"
-          Outputs="$(BaseIntermediateOutputPath)ExtractToolsetPackages.complete">
-    <ItemGroup>
-      <ToolsetPackage Include="Microsoft.DotNet.Arcade.Sdk" SourceFolder="$(PrebuiltSourceBuiltPackagesPath)" Version="$(ARCADE_BOOTSTRAP_VERSION)" />
-      <ToolsetPackage Include="Microsoft.Build.NoTargets" SourceFolder="$(ReferencePackagesDir)" Version="$(NOTARGETS_BOOTSTRAP_VERSION)" />
-      <ToolsetPackage Include="Microsoft.Build.Traversal" SourceFolder="$(ReferencePackagesDir)" Version="$(TRAVERSAL_BOOTSTRAP_VERSION)" />
-    </ItemGroup>
-
-    <Unzip SourceFiles="%(ToolsetPackage.SourceFolder)%(ToolsetPackage.Identity).%(ToolsetPackage.Version).nupkg"
-           DestinationFolder="$(BootstrapPackagesDir)$([System.String]::Copy('%(ToolsetPackage.Identity)').ToLowerInvariant())/%(ToolsetPackage.Version)"
-           SkipUnchangedFiles="true" />
-
-    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
-    <Touch Files="$(BaseIntermediateOutputPath)ExtractToolsetPackages.complete" AlwaysCreate="true">
-      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
-    </Touch>
-  </Target>
-
-  <UsingTask TaskName="Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.MarkAndCatalogPackages" AssemblyFile="$(MicrosoftDotNetSourceBuildTasksLeakDetectionAssembly)" TaskFactory="TaskHostFactory" Condition="'$(EnablePoison)' == 'true'" />
-  <Target Name="PoisonPrebuiltPackages"
-          Condition="'$(EnablePoison)' == 'true'"
-          Inputs="$(MSBuildProjectFullPath)"
-          Outputs="$(BaseIntermediateOutputPath)PoisonPrebuiltPackages.complete">
-    <PropertyGroup>
-      <SourceBuiltPoisonMarkerFile>.source-built.xml</SourceBuiltPoisonMarkerFile>
-      <SourceBuiltPoisonReportDataFile>$(PackageReportDir)poison-source-built-catalog.xml</SourceBuiltPoisonReportDataFile>
-    </PropertyGroup>
-
-    <ItemGroup>
-      <PrebuiltPackages Include="$(PrebuiltPackagesPath)**/*.nupkg" />
-      <PrebuiltSourceBuiltPackages Include="$(PrebuiltSourceBuiltPackagesPath)**/*.nupkg" />
-    </ItemGroup>
-
-    <Message Importance="High" Text="[$([System.DateTime]::Now.ToString('HH:mm:ss.ff'))] Poisoning existing packages for leak detection." />
-
-    <MarkAndCatalogPackages PackagesToMark="@(PrebuiltPackages)" CatalogOutputFilePath="$(PoisonReportDataFile)" MarkerFileName="$(PoisonMarkerFile)" />
-    <MarkAndCatalogPackages PackagesToMark="@(PrebuiltSourceBuiltPackages)" CatalogOutputFilePath="$(SourceBuiltPoisonReportDataFile)" MarkerFileName="$(SourceBuiltPoisonMarkerFile)" />
-
-    <Message Importance="High" Text="[$([System.DateTime]::Now.ToString('HH:mm:ss.ff'))] Done poisoning." />
-
-    <MakeDir Directories="$(BaseIntermediateOutputPath)" />
-    <Touch Files="$(BaseIntermediateOutputPath)PoisonPrebuiltPackages.complete" AlwaysCreate="true">
-      <Output TaskParameter="TouchedFiles" ItemName="FileWrites" />
-    </Touch>
-  </Target>
-
-</Project>
diff --git a/src/SourceBuild/content/eng/tools/tasks/Directory.Build.props b/src/SourceBuild/content/eng/tools/tasks/Directory.Build.props
deleted file mode 100644
index 7c1442273..000000000
--- a/src/SourceBuild/content/eng/tools/tasks/Directory.Build.props
+++ /dev/null
@@ -1,21 +0,0 @@
-<Project>
-
-  <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props, $(MSBuildThisFileDirectory)..))" />
-
-  <PropertyGroup>
-    <RestoreSources Condition="'$(DotNetBuildSourceOnly)' == 'true'">$(ReferencePackagesDir);$(PrebuiltPackagesPath);$(PrebuiltSourceBuiltPackagesPath)</RestoreSources>
-  </PropertyGroup>
-
-  <!--
-    Use some assemblies from the SDK, instead of package references. This ensures they match what's
-    found when the task is loaded by the SDK's MSBuild.
-    Reference NuGet assemblies, except a command line assembly that causes warnings such as:
-    MSB3277: Found conflicts between different versions of "System.Collections" that could not be resolved.
-  -->
-  <ItemGroup>
-    <SdkAssembly Include="$([MSBuild]::NormalizePath('$(NetCoreRoot)', 'sdk', '$(NETCoreSdkVersion)', 'Newtonsoft.Json.dll'));
-                          $([MSBuild]::NormalizeDirectory('$(NetCoreRoot)', 'sdk', '$(NETCoreSdkVersion)'))NuGet.*.dll"
-                 Exclude="$([MSBuild]::NormalizePath('$(NetCoreRoot)', 'sdk', '$(NETCoreSdkVersion)', 'NuGet.CommandLine.XPlat.dll'))" />
-  </ItemGroup>
-
-</Project>
diff --git a/src/SourceBuild/content/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Directory.Build.props b/src/SourceBuild/content/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Directory.Build.props
new file mode 100644
index 000000000..6e73e409c
--- /dev/null
+++ b/src/SourceBuild/content/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Directory.Build.props
@@ -0,0 +1,13 @@
+<Project>
+
+  <!--
+    Do not import the Arcade SDK as this would introduce a prebuilt as this project builds
+    the custom sdk resolver that makes the bootstrap toolsets available.
+  -->
+  <PropertyGroup>
+    <SkipArcadeSdkImport>true</SkipArcadeSdkImport>
+  </PropertyGroup>
+
+  <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props, $(MSBuildThisFileDirectory)..))" />
+
+</Project>
diff --git a/src/SourceBuild/content/eng/tools/tools.proj b/src/SourceBuild/content/eng/tools/tools.proj
new file mode 100644
index 000000000..df5292004
--- /dev/null
+++ b/src/SourceBuild/content/eng/tools/tools.proj
@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.Build.Traversal">
+
+  <ItemGroup>
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.UnifiedBuild.Tasks\Microsoft.DotNet.UnifiedBuild.Tasks.csproj" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(DotNetBuildSourceOnly)' == 'true'">
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.SourceBuild.Tasks.LeakDetection\Microsoft.DotNet.SourceBuild.Tasks.LeakDetection.csproj" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(DotNetBuildSourceOnly)' != 'true'">
+    <!-- Skip the sdk resolver in source-only mode as it already got built in the previous msbuild node execution triggered in build.sh. -->
+    <ProjectReference Include="$(TasksDir)Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver\Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj" />
+  </ItemGroup>
+
+</Project>