diff --git a/eng/Versions.props b/eng/Versions.props
index 2cc105534..8c25cd8b8 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -159,8 +159,20 @@
          removed.  See https://github.com/dotnet/source-build/issues/2295 -->
     <MicrosoftBuildFrameworkVersion>15.7.179</MicrosoftBuildFrameworkVersion>
     <MicrosoftBuildUtilitiesCoreVersion>15.7.179</MicrosoftBuildUtilitiesCoreVersion>
+    <!--
+      Building .NET from source depends on one or two tar.gz files depending on the branch's current
+      source-buildability status.
+
+      PrivateSourceBuiltArtifactsPackageVersion is a tar.gz of .NET build outputs from a previous
+      build needed to build the current version of .NET. This is always defined, because .NET needs
+      to be bootstrappable at any point in time.
+
+      PrivateSourceBuiltPrebuiltsPackageVersion is a tar.gz of assets downloaded from the internet
+      that are needed to build the current version of .NET. Early in the lifecycle of a .NET major
+      or minor release, prebuilts may be needed. When the release is mature, prebuilts are not
+      necessary, and this property is removed from the file.
+    -->
     <PrivateSourceBuiltArtifactsPackageVersion>0.1.0-6.0.100-bootstrap.29</PrivateSourceBuiltArtifactsPackageVersion>
-    <PrivateSourceBuiltPrebuiltsPackageVersion>0.1.0-6.0.100-36</PrivateSourceBuiltPrebuiltsPackageVersion>
   </PropertyGroup>
   <!-- Workload manifest package versions -->
   <PropertyGroup>
diff --git a/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets b/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets
index 7203b401b..c970f04cc 100644
--- a/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets
+++ b/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets
@@ -292,7 +292,9 @@
 
     <ItemGroup>
       <ArtifactUrls Include="$(SourceBuiltArtifactsTarballUrl)$(SourceBuiltArtifactsTarballName).$(PrivateSourceBuiltArtifactsPackageVersion).tar.gz" />
-      <ArtifactUrls Include="$(SourceBuiltArtifactsTarballUrl)$(SourceBuiltPrebuiltsTarballName).$(PrivateSourceBuiltPrebuiltsPackageVersion).tar.gz" />
+      <ArtifactUrls
+        Include="$(SourceBuiltArtifactsTarballUrl)$(SourceBuiltPrebuiltsTarballName).$(PrivateSourceBuiltPrebuiltsPackageVersion).tar.gz"
+        Condition="'$(PrivateSourceBuiltPrebuiltsPackageVersion)' != ''" />
     </ItemGroup>
 
     <WriteLinesToFile
diff --git a/src/SourceBuild/tarball/content/build.proj b/src/SourceBuild/tarball/content/build.proj
index 117a13675..3a43b32ab 100644
--- a/src/SourceBuild/tarball/content/build.proj
+++ b/src/SourceBuild/tarball/content/build.proj
@@ -133,8 +133,22 @@
   </Target>
 
   <Target Name="CreatePrebuiltsTarball"
-          AfterTargets="Build">
+          AfterTargets="Build"
+          DependsOnTargets="
+            CheckIfPrebuiltsExistToPack;
+            CreatePrebuiltsTarballIfPrebuiltsExist"/>
 
+  <Target Name="CheckIfPrebuiltsExistToPack">
+    <!-- Directory existence doesn't mean there are files inside. Use a pattern to find files. -->
+    <ItemGroup>
+      <PrebuiltFile Include="$(ResultingPrebuiltPackagesDir)**" />
+    </ItemGroup>
+
+    <Message Text="Found @(PrebuiltFile->Count()) files in prebuilt packages dir." Importance="High" />
+  </Target>
+
+  <Target Name="CreatePrebuiltsTarballIfPrebuiltsExist"
+          Condition="'@(PrebuiltFile->Count())' != '0'">
     <PropertyGroup>
       <TarballFileVersion>$(PrivateSourceBuiltPrebuiltsPackageVersionPrefix)$([MSBuild]::Add($(PrivateSourceBuiltPrebuiltsPackageVersionSuffix), 1))</TarballFileVersion>
       <TarballFilePath>$(OutputPath)$(SourceBuiltPrebuiltsTarballName).$(TarballFileVersion).tar.gz</TarballFilePath>
diff --git a/src/SourceBuild/tarball/content/tools-local/init-build.proj b/src/SourceBuild/tarball/content/tools-local/init-build.proj
index 3835e019c..c5494dedd 100644
--- a/src/SourceBuild/tarball/content/tools-local/init-build.proj
+++ b/src/SourceBuild/tarball/content/tools-local/init-build.proj
@@ -46,8 +46,16 @@
           WorkingDirectory="$(PrebuiltSourceBuiltPackagesPath)"
           Condition="'$(CustomPrebuiltSourceBuiltPackagesPath)' == ''" />
 
-    <Exec Command="tar -xzf $(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*.tar.gz"
-          WorkingDirectory="$(PrebuiltPackagesPath)" />
+    <!--
+      Check for a prebuilt dependency tarball and extract if exists. If there isn't one, we expect
+      the build to be working without prebuilts.
+    -->
+    <ItemGroup>
+      <SourceBuiltPrebuiltsTarballFile Include="$(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*.tar.gz" />
+    </ItemGroup>
+    <Exec Command="tar -xzf %(SourceBuiltPrebuiltsTarballFile.FullPath)"
+          WorkingDirectory="$(PrebuiltPackagesPath)"
+          Condition="'@(SourceBuiltPrebuiltsTarballFile)' != ''" />
 
     <!-- Move SBRP packages to reference packages location -->
     <MakeDir Directories="$(ReferencePackagesDir)" />