diff --git a/NuGet.config b/NuGet.config
index b004e5cc..e32bddfd 100644
--- a/NuGet.config
+++ b/NuGet.config
@@ -2,6 +2,6 @@
 <configuration>
   <packageSources>
     <clear />
-    <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
+    <!-- Restore sources should be defined in build/sources.props. -->
   </packageSources>
-</configuration>
\ No newline at end of file
+</configuration>
diff --git a/build/PackageArchive.targets b/build/PackageArchive.targets
index 666cade7..ad5d9ce0 100644
--- a/build/PackageArchive.targets
+++ b/build/PackageArchive.targets
@@ -46,7 +46,7 @@
     <MSBuild
       Projects="$(_WorkRoot)Archive.csproj"
       Targets="Restore"
-      Properties="RestorePackagesPath=$(FallbackStagingDir);RuntimeFrameworkVersion=$(MicrosoftNETCoreApp21PackageVersion);DotNetRestoreSourcePropsPath=$(GeneratedFallbackRestoreSourcesPropsPath);AspNetUniverseBuildOffline=true" />
+      Properties="RestorePackagesPath=$(FallbackStagingDir);RuntimeFrameworkVersion=$(MicrosoftNETCoreApp21PackageVersion);DotNetRestoreSourcePropsPath=$(GeneratedFallbackRestoreSourcesPropsPath);DotNetBuildOffline=true;AspNetUniverseBuildOffline=true" />
 
     <!-- Create the archive -->
     <Exec Command="$(ArchiverPath) -a $(FallbackOutputPath) $(FallbackStagingDir)" />
diff --git a/build/SharedFx.targets b/build/SharedFx.targets
index c536a807..31a7da02 100644
--- a/build/SharedFx.targets
+++ b/build/SharedFx.targets
@@ -28,7 +28,11 @@
     <PropertyGroup>
       <MetapackageSource>$(_MetapackageSrcRoot)$(MetapackageName)\</MetapackageSource>
       <MetapackageWorkDirectory>$(_WorkRoot)$(MetapackageName)\</MetapackageWorkDirectory>
-      <CommonProps>Configuration=$(Configuration);DotNetRestoreSourcePropsPath=$(GeneratedRestoreSourcesPropsPath);AspNetUniverseBuildOffline=true</CommonProps>
+      <CommonProps />
+      <CommonProps>$(CommonProps);Configuration=$(Configuration)</CommonProps>
+      <CommonProps>$(CommonProps);DotNetRestoreSourcePropsPath=$(GeneratedRestoreSourcesPropsPath)</CommonProps>
+      <CommonProps>$(CommonProps);DotNetBuildOffline=true</CommonProps>
+      <CommonProps>$(CommonProps);AspNetUniverseBuildOffline=true</CommonProps>
       <CommonProps>$(CommonProps);RuntimeFrameworkVersion=$(MicrosoftNETCoreApp21PackageVersion)</CommonProps>
       <CommonProps>$(CommonProps);AppMetapackageVersion=$(PackageVersion)</CommonProps>
     </PropertyGroup>
@@ -121,6 +125,7 @@
 
       <CommonSharedFxProps>Configuration=$(Configuration);RuntimeIdentifier=$(SharedFxRestoreRid)</CommonSharedFxProps>
       <CommonSharedFxProps>$(CommonSharedFxProps);DotNetRestoreSourcePropsPath=$(GeneratedRestoreSourcesPropsPath)</CommonSharedFxProps>
+      <CommonSharedFxProps>$(CommonSharedFxProps);DotNetBuildOffline=true</CommonSharedFxProps>
       <CommonSharedFxProps>$(CommonSharedFxProps);AspNetUniverseBuildOffline=true</CommonSharedFxProps>
     </PropertyGroup>
   </Target>
diff --git a/build/sources.props b/build/sources.props
index 2d82aa8a..2d011505 100644
--- a/build/sources.props
+++ b/build/sources.props
@@ -1,11 +1,17 @@
 <Project>
+
+  <Import Project="$(DotNetRestoreSourcePropsPath)" Condition="'$(DotNetRestoreSourcePropsPath)' != ''"/>
+
   <PropertyGroup>
-    <RestoreSources>$(DotNetAdditionalRestoreSources)</RestoreSources>
     <RestoreSources>
+      $(DotNetAdditionalRestoreSources);
+      $(DotNetRestoreSources);
+    </RestoreSources>
+    <RestoreSources Condition=" '$(DotNetBuildOffline)' != 'true' ">
       $(RestoreSources);
       https://api.nuget.org/v3/index.json;
     </RestoreSources>
-    <RestoreSources Condition=" '$(DisableMyGetRestoreSources)' != 'true' ">
+    <RestoreSources Condition=" '$(DotNetBuildOffline)' != 'true' AND '$(DisableMyGetRestoreSources)' != 'true' ">
       $(RestoreSources);
       https://dotnet.myget.org/F/dotnet-core/api/v3/index.json;
       https://dotnet.myget.org/F/aspnetcore-tools/api/v3/index.json;
diff --git a/build/tools/templates/Archive/Archive.csproj b/build/tools/templates/Archive/Archive.csproj
index d5d5c940..3d3d608b 100644
--- a/build/tools/templates/Archive/Archive.csproj
+++ b/build/tools/templates/Archive/Archive.csproj
@@ -6,6 +6,7 @@
     <TargetFramework>netcoreapp2.1</TargetFramework>
     <EnableApiCheck>false</EnableApiCheck>
     <DotnetCliToolTargetFramework>netcoreapp2.1</DotnetCliToolTargetFramework>
+    <RestoreSources>$(RestoreSources);$(DotNetRestoreSources);</RestoreSources>
   </PropertyGroup>
 
 </Project>
diff --git a/build/tools/templates/SharedFx/SharedFx.csproj b/build/tools/templates/SharedFx/SharedFx.csproj
index 39bc5fb9..24bd3aad 100644
--- a/build/tools/templates/SharedFx/SharedFx.csproj
+++ b/build/tools/templates/SharedFx/SharedFx.csproj
@@ -6,6 +6,7 @@
     <TargetFramework>netcoreapp2.1</TargetFramework>
     <DisableImplicitNuGetFallbackFolder>true</DisableImplicitNuGetFallbackFolder>
     <DisableImplicitFrameworkReferences>true</DisableImplicitFrameworkReferences>
+    <RestoreSources>$(RestoreSources);$(DotNetRestoreSources);</RestoreSources>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Directory.Build.props b/src/Directory.Build.props
index 94f49d1b..79ca86d0 100644
--- a/src/Directory.Build.props
+++ b/src/Directory.Build.props
@@ -2,4 +2,5 @@
   <Import Project="..\version.props" />
   <Import Project="..\build\common.props" />
   <Import Project="..\build\external-dependencies.props" />
+  <Import Project="..\build\sources.props" />
 </Project>