diff --git a/DEVGUIDE.md b/DEVGUIDE.md
index d81788c893d..d5b58b32757 100644
--- a/DEVGUIDE.md
+++ b/DEVGUIDE.md
@@ -31,9 +31,10 @@ There are various qualifiers:
     build.cmd debug           -- build debug instead of release
 
     build.cmd proto           -- force the rebuild of the Proto bootstrap compiler in addition to other things
+    build.cmd protofx         -- build using a .NET Framework proto (no .NET Core is used)
 
-    build.cmd coreclr         -- build/tests only the coreclr version compiler (not the Visual F# IDE Tools)
-    build.cmd compiler        -- build/tests only the compiler (not the Visual F# IDE Tools)
+    build.cmd net40           -- build/tests for .NET Framework version of the compiler (not the Visual F# IDE Tools or .NET Core)
+    build.cmd coreclr         -- build/tests only the coreclr version compiler (not the Visual F# IDE Tools or .NET Framework)
     build.cmd vs              -- build/tests the Visual F# IDE Tools
     build.cmd pcls            -- build/tests the PCL FSharp.Core libraries
 
@@ -44,7 +45,7 @@ There are various qualifiers:
 
     build.cmd test-smoke      -- build, run smoke tests
     build.cmd test-coreunit   -- build, run FSharp.Core tests
-    build.cmd test-coreclr    -- build, run CoreCLR tests
+    build.cmd test-coreclr    -- build, run .NET Core tests
     build.cmd test-pcls       -- build, run PCL tests
     build.cmd test-fsharp     -- build, run tests\fsharp suite
     build.cmd test-fsharpqa   -- build, run tests\fsharpqa suite
diff --git a/build.cmd b/build.cmd
index 55b66c447ba..4608fb43cb8 100644
--- a/build.cmd
+++ b/build.cmd
@@ -26,6 +26,8 @@ exit /b 1
 
 :ARGUMENTS_OK
 
+set BUILD_PROTO_WITH_CORECLR_LKG=1
+
 set BUILD_PROTO=0
 set BUILD_NET40=1
 set BUILD_CORECLR=0
@@ -100,6 +102,11 @@ if /i '%ARG%' == 'all' (
     set SKIP_EXPENSIVE_TESTS=0
 )
 
+if /i '%ARG%' == 'protofx' (
+    set BUILD_PROTO_WITH_CORECLR_LKG=0
+    set BUILD_PROTO=1
+)
+
 if /i '%ARG%' == 'microbuild' (
     set BUILD_PROTO=1
     set BUILD_NET40=1
@@ -257,6 +264,7 @@ REM after this point, ARG variable should not be used, use only BUILD_* or TEST_
 echo Build/Tests configuration:
 echo.
 echo BUILD_PROTO=%BUILD_PROTO%
+echo BUILD_PROTO_WITH_CORECLR_LKG=%BUILD_PROTO_WITH_CORECLR_LKG%
 echo BUILD_NET40=%BUILD_NET40%
 echo BUILD_CORECLR=%BUILD_CORECLR%
 echo BUILD_PORTABLE=%BUILD_PORTABLE%
@@ -327,7 +335,7 @@ if '%RestorePackages%' == 'true' (
     .\.nuget\NuGet.exe restore packages.config -PackagesDirectory packages -ConfigFile .nuget\nuget.config
     @if ERRORLEVEL 1 echo Error: Nuget restore failed  && goto :failure
 )
-if '%BUILD_CORECLR%' == '1' (
+if '%BUILD_PROTO_WITH_CORECLR_LKG%' == '1' (
 
     :: Restore the Tools directory
     call %~dp0init-tools.cmd
@@ -358,6 +366,10 @@ if '%BUILD_CORECLR%' == '1' (
     popd
 
 )
+if '%BUILD_PROTO_WITH_CORECLR_LKG%' == '0' (
+    rmdir /s .\lkg\bin\debug
+)
+
 rem copy targestfile into tools directory ... temporary fix until packaging complete.
 copy src\fsharp\FSharp.Build\Microsoft.FSharp.targets tools\Microsoft.FSharp.targets
 copy src\fsharp\FSharp.Build\Microsoft.Portable.FSharp.targets tools\Microsoft.Portable.FSharp.targets
diff --git a/src/FSharpSource.targets b/src/FSharpSource.targets
index 617313d2fbb..315cee7ac13 100644
--- a/src/FSharpSource.targets
+++ b/src/FSharpSource.targets
@@ -739,12 +739,25 @@
 
   <Choose>
     <When Condition="'$(BuildWith)' == 'LKG'">
-      <PropertyGroup>
-         <FSharpTargetsPath>..\lkg\FSharp-$(LkgVersion)\bin\Microsoft.FSharp.Targets</FSharpTargetsPath>
-         <FscToolPath>$(FSharpSourcesRoot)\..\lkg\bin\Debug\netstandard1.6\win7-x64\publish</FscToolPath>
-         <FSLKGPath>$(FSharpSourcesRoot)\..\lkg\FSharp-$(LkgVersion)\bin</FSLKGPath>
-         <FSCoreLKGPath>$(FSLKGPath)\FSharp.Core.dll</FSCoreLKGPath>
-      </PropertyGroup>
+      <Choose>
+        <When Condition="Exists('$(FSharpSourcesRoot)\..\lkg\bin\Debug\netstandard1.6\win7-x64\publish\fsc.exe')">
+          <PropertyGroup >
+            <FSharpTargetsPath>$(FSharpSourcesRoot)\..\lkg\FSharp-$(LkgVersion)\bin\Microsoft.FSharp.Targets</FSharpTargetsPath>
+            <FscToolPath>$(FSharpSourcesRoot)\..\lkg\bin\Debug\netstandard1.6\win7-x64\publish</FscToolPath>
+            <FSLKGPath>$(FSharpSourcesRoot)\..\lkg\FSharp-$(LkgVersion)\bin</FSLKGPath>
+            <FSCoreLKGPath>$(FSLKGPath)\FSharp.Core.dll</FSCoreLKGPath>
+          </PropertyGroup>
+        </When>
+        <Otherwise>
+          <PropertyGroup >
+            <FSharpTargetsPath>..\lkg\FSharp-$(LkgVersion)\bin\Microsoft.FSharp.Targets</FSharpTargetsPath>
+            <FscToolPath>$(FSharpSourcesRoot)\..\lkg\FSharp-$(LkgVersion)\bin</FscToolPath>
+            <FSLKGPath>$(FSharpSourcesRoot)\..\lkg\FSharp-$(LkgVersion)\bin</FSLKGPath>
+            <FSCoreLKGPath>$(FSLKGPath)\FSharp.Core.dll</FSCoreLKGPath>
+          </PropertyGroup>
+        </Otherwise>
+      </Choose>
+		
     </When>
     <When Condition="'$(TargetFramework)'=='portable47' OR '$(TargetFramework)'=='portable7' OR '$(TargetFramework)'=='portable78' OR '$(TargetFramework)'=='portable259' OR '$(TargetFramework)'=='coreclr'">
       <PropertyGroup>