diff --git a/docs/contributing/Building, Debugging, and Testing on Windows.md b/docs/contributing/Building, Debugging, and Testing on Windows.md
index 7806603b9f21178efb3a4bd20f5dde27f9a18a02..087a4f5657ec3a1d31f30f6a4feb15a0a9f85c21 100644
--- a/docs/contributing/Building, Debugging, and Testing on Windows.md	
+++ b/docs/contributing/Building, Debugging, and Testing on Windows.md	
@@ -11,24 +11,19 @@ Using the command line Roslyn can be developed using the following pattern:
 
 ## Recommended version of .NET Framework
 
-The minimal required version of .NET Framework is 4.6, however 4.7.2 is recommended for best developer experience.
+The minimal required version of .NET Framework is 4.7.2.
 
-The projects in this repository are configured to build with Portable PDBs, which are supported in stack traces starting with .NET Framework 4.7.2.
-If a stack trace is displayed on .NET Framework older than 4.7.2 (e.g. by xUnit when a test fails) it won't contain source and line information.
+## Developing with Visual Studio 2019
 
-.NET Framework 4.7.2 is included in [Windows 10 April 2018 Update](https://blogs.windows.com/windowsexperience/2018/04/30/how-to-get-the-windows-10-april-2018-update/). It can also be installed from the [Microsoft Download Center](https://www.microsoft.com/net/download/dotnet-framework-runtime).
-
-## Developing with Visual Studio 2017
-
-1. [Visual Studio 2017 Version 15.7](https://www.visualstudio.com/vs/preview/)
+1. [Visual Studio 2019 Preview 4](https://www.visualstudio.com/vs/preview/)
     - Ensure C#, VB, MSBuild, .NET Core and Visual Studio Extensibility are included in the selected work loads
-    - Ensure Visual Studio is on Version "15.7" or greater
+    - Ensure Visual Studio is on Version "Preview 4" or greater
 1. [.NET Core SDK 2.1.401](https://www.microsoft.com/net/download/core) (the installers are: [Windows x64 installer](https://dotnetcli.blob.core.windows.net/dotnet/Sdk/2.1.401/dotnet-sdk-2.1.401-win-x64.exe), [Windows x86 installer](https://dotnetcli.blob.core.windows.net/dotnet/Sdk/2.1.401/dotnet-sdk-2.1.401-win-x86.exe))
 1. [PowerShell 3.0 or newer](https://docs.microsoft.com/en-us/powershell/scripting/setup/installing-windows-powershell). If you are on Windows 10, you are fine; you'll only need to upgrade if you're on Windows 7. The download link is under the "upgrading existing Windows PowerShell" heading.
 1. Run Restore.cmd
 1. Open Roslyn.sln
 
-If you already installed Visual Studio and need to add the necessary work loads or move to version 15.7:
+If you already installed Visual Studio and need to add the necessary work loads or move to Preview 4:
 do the following:
 
 - Run the Visual Studio Installer from your start menu. You can just search for "Visual Studio Installer". If you can't find it, it's typically located at "C:\Program Files (x86)\Microsoft Visual Studio\Installer\vs_installer.exe"
@@ -44,7 +39,7 @@ There are a number of options for running the core Roslyn unit tests:
 
 The Test.cmd script will run our unit test on already built binaries.  It can be passed the -build arguments to force a new build before running tests.
 
-1. Run the "Developer Command Prompt for VS2017" from your start menu.
+1. Run the "Developer Command Prompt for VS2019" from your start menu.
 2. Navigate to the directory of your Git clone.
 3. Run `msbuild /v:m /m /nodereuse:false BuildAndTest.proj` in the command prompt.
 
diff --git a/eng/Versions.props b/eng/Versions.props
index b929fd225663d4b4d5b4dac570173657f0d66934..eaea26f78ccf582048f992f714ddd62cb8865151 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -73,10 +73,9 @@
     <MicrosoftMetadataVisualizerVersion>1.0.0-beta1-63011-01</MicrosoftMetadataVisualizerVersion>
     <MicrosoftMSXMLVersion>8.0.0.0-alpha</MicrosoftMSXMLVersion>
     <MicrosoftNetFrameworkReferenceAssembliesVersion>1.0.0-alpha-004</MicrosoftNetFrameworkReferenceAssembliesVersion>
-    <MicrosoftNetCompilersVersion>3.0.0-beta2-19068-12</MicrosoftNetCompilersVersion>
+    <MicrosoftNetCompilersToolsetVersion>3.1.0-beta1-19127-06</MicrosoftNetCompilersToolsetVersion>
     <MicrosoftNetCoreAnalyzersVersion>$(RoslynDiagnosticsNugetPackageVersion)</MicrosoftNetCoreAnalyzersVersion>
     <MicrosoftNetCoreILAsmVersion>2.0.0</MicrosoftNetCoreILAsmVersion>
-    <MicrosoftNETCoreCompilersVersion>3.0.0-beta2-19068-12</MicrosoftNETCoreCompilersVersion>
     <MicrosoftNETCorePlatformsVersion>2.1.0</MicrosoftNETCorePlatformsVersion>
     <MicrosoftNETCoreRuntimeCoreCLRVersion>2.0.0</MicrosoftNETCoreRuntimeCoreCLRVersion>
      <!-- Using a private build of Microsoft.Net.Test.SDK to work around issue https://github.com/Microsoft/vstest/issues/1764 -->	
@@ -288,10 +287,10 @@
     <UsingToolXUnit>true</UsingToolXUnit>
 
     <!-- 
-      Use compilers in Microsoft.NET.Compilers package unless we are building with bootstrapped compilers.
-      Allows to dogfood the latest compiler features.
+       During the transition period from Microsoft.Net.Compilers to Microsoft.Net.Compilers.Toolset
+       we are always doing custom importing here.
     -->
-    <UsingToolMicrosoftNetCompilers Condition="'$(BootstrapBuildPath)' == ''">true</UsingToolMicrosoftNetCompilers>
+    <UsingToolMicrosoftNetCompilers>false</UsingToolMicrosoftNetCompilers>
   </PropertyGroup>
 
   <PropertyGroup>
diff --git a/eng/targets/Settings.props b/eng/targets/Settings.props
index 5a0dfadc60b449c2a63b7dd4c0b63312e087e415..7fb7fba2a0672facfff5ed510f44e64496a74d3f 100644
--- a/eng/targets/Settings.props
+++ b/eng/targets/Settings.props
@@ -130,6 +130,14 @@
   -->
   <Import Project="Bootstrap.props" Condition="'$(BootstrapBuildPath)' != ''" />
 
+  <!--
+     During the transition period from Microsoft.Net.Compilers to Microsoft.Net.Compilers.Toolset
+     we need our own PackageReference
+  -->
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Net.Compilers.Toolset" Version="$(MicrosoftNetCompilersToolsetVersion)" Condition="'$(BootstrapBuildPath)' == ''" PrivateAssets="all" IsImplicitlyDefined="true" />
+  </ItemGroup>
+
   <!--
     Analyzers
   -->
@@ -188,7 +196,7 @@
     <!-- C# specific settings -->
     <When Condition="'$(Language)' == 'C#'">
       <PropertyGroup>
-        <LangVersion>7.3</LangVersion>
+        <LangVersion>8.0</LangVersion>
         <WarningLevel>4</WarningLevel>
         <ErrorReport>prompt</ErrorReport>
 
diff --git a/src/Compilers/Core/Portable/Operations/ControlFlowGraphBuilder.cs b/src/Compilers/Core/Portable/Operations/ControlFlowGraphBuilder.cs
index f99f27341227ee7b5cbe0c33fcc98b1c534b664d..44afb4d5b1b12a00140a6f8eba7c64a245c9c908 100644
--- a/src/Compilers/Core/Portable/Operations/ControlFlowGraphBuilder.cs
+++ b/src/Compilers/Core/Portable/Operations/ControlFlowGraphBuilder.cs
@@ -311,7 +311,7 @@ void followBranch(BasicBlockBuilder current, in BasicBlockBuilder.Branch branch)
             }
 
             // Returns whether we should proceed to the destination after finallies were taken care of.
-            bool stepThroughFinally(ControlFlowRegion region, BasicBlockBuilder destination)
+            static bool stepThroughFinally(ControlFlowRegion region, BasicBlockBuilder destination)
             {
                 int destinationOrdinal = destination.Ordinal;
                 while (!region.ContainsBlock(destinationOrdinal))