diff --git a/BuildToolsVersion.txt b/BuildToolsVersion.txt
index 57adb361f015..b0667ae58b16 100644
--- a/BuildToolsVersion.txt
+++ b/BuildToolsVersion.txt
@@ -1 +1 @@
-1.0.25-prerelease-00156
+1.0.25-prerelease-00157
diff --git a/build.sh b/build.sh
index dd8f6ca4d5c0..d6fea0009926 100755
--- a/build.sh
+++ b/build.sh
@@ -133,7 +133,7 @@ build_managed_corefx()
     __buildproj=$__scriptpath/build.proj
     __buildlog=$__scriptpath/msbuild.log
 
-    MONO29679=1 ReferenceAssemblyRoot=$__referenceassemblyroot mono $__msbuildpath "$__buildproj" /nologo /verbosity:minimal "/fileloggerparameters:Verbosity=normal;LogFile=$__buildlog" /t:Build /p:OSGroup=$__BuildOS /p:COMPUTERNAME=$(hostname) /p:USERNAME=$(id -un) /p:TestNugetRuntimeId=$__TestNugetRuntimeId /p:ToolNugetRuntimeId=$__TestNugetRuntimeId $__UnprocessedBuildArgs
+    ReferenceAssemblyRoot=$__referenceassemblyroot $__scriptpath/Tools/corerun $__scriptpath/Tools/MSBuild.exe "$__buildproj" /nologo /verbosity:minimal "/fileloggerparameters:Verbosity=normal;LogFile=$__buildlog" /t:Build /p:OSGroup=$__BuildOS /p:COMPUTERNAME=$(hostname) /p:USERNAME=$(id -un) /p:TestNugetRuntimeId=$__TestNugetRuntimeId /p:ToolNugetRuntimeId=$__TestNugetRuntimeId $__UnprocessedBuildArgs
     BUILDERRORLEVEL=$?
 
     echo
diff --git a/dir.props b/dir.props
index f5756958fd25..535db0a346c8 100644
--- a/dir.props
+++ b/dir.props
@@ -6,6 +6,8 @@
     $(OS) is set to Unix/Windows_NT. This comes from an environment variable on Windows and MSBuild on Unix.
   -->
   <PropertyGroup>
+    <!-- Temp change to make OS X build behave as a Linux build -->
+    <OsEnvironment Condition="'$(OsEnvironment)'=='' AND '$(OS)'=='OSX'">Unix</OsEnvironment>
     <OsEnvironment Condition="'$(OsEnvironment)'==''">$(OS)</OsEnvironment>
   </PropertyGroup>
 
@@ -35,7 +37,7 @@
   <!-- Common repo directories -->
   <PropertyGroup>
     <ProjectDir>$(MSBuildThisFileDirectory)</ProjectDir>
-    <SourceDir>$(ProjectDir)src\</SourceDir>
+    <SourceDir>$(ProjectDir)src/</SourceDir>
 
     <!-- Output directories -->
     <BinDir Condition="'$(BinDir)'==''">$(ProjectDir)bin/</BinDir>
@@ -120,7 +122,6 @@
     <!-- Need to escape double forward slash (%2F) or MSBuild will normalize to one slash on Unix. -->
 
     <DnuSourceList Include="https:%2F%2Fwww.myget.org/F/dotnet-core/" />
-    <DnuSourceList Include="https:%2F%2Fwww.myget.org/F/dotnet-coreclr/" />
     <DnuSourceList Include="https:%2F%2Fwww.myget.org/F/dotnet-corefxtestdata/" />
     <DnuSourceList Include="https:%2F%2Fwww.myget.org/F/dotnet-buildtools/" />
     <DnuSourceList Include="https:%2F%2Fwww.nuget.org/api/v2/" />
@@ -128,20 +129,20 @@
 
   <!-- list of directories to perform batch restore -->
   <ItemGroup>
-    <DnuRestoreDir Include="$(MSBuildProjectDirectory)\src" />
+    <DnuRestoreDir Include="$(MSBuildProjectDirectory)/src" />
     <DnuRestoreDir Include="$(ToolsDir)" />
     <!-- workaround to address issue where DNX won't recurse directories under a project.json
          https://github.com/aspnet/dnx/commit/0dda8bf86863364cc20421f1af7494f1b2a3256f -->
-    <DnuRestoreDir Include="$(MSBuildProjectDirectory)\src\*\src\**\project.json" />
-    <DnuRestoreDir Include="$(MSBuildProjectDirectory)\src\*\ref\*\project.json" />
-    <DnuRestoreDir Include="$(MSBuildProjectDirectory)\src\*\tests\*\project.json" />
-    <DnuRestoreDir Include="$(MSBuildProjectDirectory)\src\*\*\netcore50aot\project.json" />
-    <DnuRestoreDir Include="$(MSBuildProjectDirectory)\src\Common\tests\**\project.json" />
+    <DnuRestoreDir Include="$(MSBuildProjectDirectory)/src/*/src/**/project.json" />
+    <DnuRestoreDir Include="$(MSBuildProjectDirectory)/src/*/ref/*/project.json" />
+    <DnuRestoreDir Include="$(MSBuildProjectDirectory)/src/*/tests/*/project.json" />
+    <DnuRestoreDir Include="$(MSBuildProjectDirectory)/src/*/*/netcore50aot/project.json" />
+    <DnuRestoreDir Include="$(MSBuildProjectDirectory)/src/Common/tests/**/project.json" />
   </ItemGroup>
 
   <PropertyGroup>
     <DnxPackageDir Condition="'$(DnxPackageDir)'==''">$(PackagesDir)/$(DnxPackageName)/</DnxPackageDir>
-    <DnuToolPath Condition="'$(DnuToolPath)'=='' and '$(OsEnvironment)'!='Unix'">$(DnxPackageDir)\bin\dnu.cmd</DnuToolPath>
+    <DnuToolPath Condition="'$(DnuToolPath)'=='' and '$(OsEnvironment)'!='Unix'">$(DnxPackageDir)/bin/dnu.cmd</DnuToolPath>
     <DnuToolPath Condition="'$(DnuToolPath)'=='' and '$(OsEnvironment)'=='Unix'">$(DnxPackageDir)/bin/dnu</DnuToolPath>
     <DotnetToolCommand Condition="'$(DotnetToolCommand)' == '' and '$(OsEnvironment)'!='Unix'">$(DotnetCliPath)dotnet.exe</DotnetToolCommand>
     <DotnetToolCommand Condition="'$(DotnetToolCommand)' == '' and '$(OsEnvironment)'=='Unix'">$(DotnetCliPath)dotnet</DotnetToolCommand>
@@ -158,7 +159,7 @@
 
   <!-- Create a collection of all project.json files for dependency updates. -->
   <ItemGroup>
-    <ProjectJsonFiles Include="$(SourceDir)**\project.json" />
+    <ProjectJsonFiles Include="$(SourceDir)**/project.json" />
   </ItemGroup>
 
   <PropertyGroup Condition="'$(BuildAllProjects)'=='true'">
@@ -186,6 +187,12 @@
     -->
     <UseECMAKey>false</UseECMAKey>
 
+    <!--
+      Full signing with Open key doesn't work with Portable Csc.
+      https://github.com/dotnet/roslyn/issues/8210
+    -->
+    <UseOpenKey>false</UseOpenKey>
+
     <!--
       Mono currently doesn't include VB targets for portable, notably /lib/mono/xbuild/Microsoft/Portable/v4.5/Microsoft.Portable.VisualBasic.targets.
       Fixed in https://github.com/mono/mono/pull/1726.
@@ -414,23 +421,23 @@
 
   <!-- Set up some common paths -->
   <PropertyGroup>
-    <CommonPath>$(SourceDir)Common\src</CommonPath>
-    <CommonTestPath>$(SourceDir)Common\tests</CommonTestPath>
+    <CommonPath>$(SourceDir)Common/src</CommonPath>
+    <CommonTestPath>$(SourceDir)Common/tests</CommonTestPath>
   </PropertyGroup>
 
   <!-- Set up the default output and intermediate paths -->
   <PropertyGroup>
     <OSPlatformConfig>$(OSGroup).$(Platform).$(ConfigurationGroup)</OSPlatformConfig>
-    <TargetOutputRelPath Condition="'$(TargetGroup)'!=''">$(TargetGroup)\</TargetOutputRelPath>
+    <TargetOutputRelPath Condition="'$(TargetGroup)'!=''">$(TargetGroup)/</TargetOutputRelPath>
 
     <BaseOutputPath Condition="'$(BaseOutputPath)'==''">$(BinDir)</BaseOutputPath>
-    <OutputPath Condition="'$(OutputPath)'==''">$(BaseOutputPath)$(OSPlatformConfig)\$(MSBuildProjectName)\$(TargetOutputRelPath)</OutputPath>
+    <OutputPath Condition="'$(OutputPath)'==''">$(BaseOutputPath)$(OSPlatformConfig)/$(MSBuildProjectName)/$(TargetOutputRelPath)</OutputPath>
 
     <BaseIntermediateOutputPath Condition="'$(BaseIntermediateOutputPath)'==''">$(ObjDir)</BaseIntermediateOutputPath>
-    <IntermediateOutputRootPath Condition="'$(IntermediateOutputRootPath)' == ''">$(BaseIntermediateOutputPath)$(OSPlatformConfig)\</IntermediateOutputRootPath>
-    <IntermediateOutputPath Condition="'$(IntermediateOutputPath)' == ''">$(IntermediateOutputRootPath)$(MSBuildProjectName)\$(TargetOutputRelPath)</IntermediateOutputPath>
+    <IntermediateOutputRootPath Condition="'$(IntermediateOutputRootPath)' == ''">$(BaseIntermediateOutputPath)$(OSPlatformConfig)/</IntermediateOutputRootPath>
+    <IntermediateOutputPath Condition="'$(IntermediateOutputPath)' == ''">$(IntermediateOutputRootPath)$(MSBuildProjectName)/$(TargetOutputRelPath)</IntermediateOutputPath>
 
-    <TestPath Condition="'$(TestPath)'==''">$(TestWorkingDir)$(OSPlatformConfig)\$(MSBuildProjectName)\</TestPath>
+    <TestPath Condition="'$(TestPath)'==''">$(TestWorkingDir)$(OSPlatformConfig)/$(MSBuildProjectName)/</TestPath>
 
     <PackagesBasePath Condition="'$(PackagesBasePath)'==''">$(BinDir)$(OSPlatformConfig)</PackagesBasePath>
   </PropertyGroup>
diff --git a/init-tools.sh b/init-tools.sh
index 1601706309bf..79e1042f0597 100755
--- a/init-tools.sh
+++ b/init-tools.sh
@@ -64,4 +64,5 @@ if [ ! -e $__PROJECT_JSON_FILE ]; then
  fi
 
  sh $__BUILD_TOOLS_PATH/init-tools.sh $__scriptpath $__DOTNET_CMD $__TOOLRUNTIME_DIR
+ chmod a+x $__TOOLRUNTIME_DIR/corerun
 fi
diff --git a/src/System.Buffers/src/System.Buffers.csproj b/src/System.Buffers/src/System.Buffers.csproj
index 8fc8d5eb7619..05b5813550db 100644
--- a/src/System.Buffers/src/System.Buffers.csproj
+++ b/src/System.Buffers/src/System.Buffers.csproj
@@ -6,7 +6,7 @@
     <ProjectGuid>{2ADDB484-6F57-4D71-A3FE-A57EC6329A2B}</ProjectGuid>
     <PackageTargetFramework>dotnet5.2</PackageTargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <UseOpenKey>true</UseOpenKey>
+    <UseOpenKey Condition="'$(UseOpenKey)'==''">true</UseOpenKey>
   </PropertyGroup>
   <!-- Default configurations to help VS understand the options -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'" />
diff --git a/src/System.Diagnostics.Contracts/src/System.Diagnostics.Contracts.csproj b/src/System.Diagnostics.Contracts/src/System.Diagnostics.Contracts.csproj
index 8562511e4cb1..14c8a0441836 100644
--- a/src/System.Diagnostics.Contracts/src/System.Diagnostics.Contracts.csproj
+++ b/src/System.Diagnostics.Contracts/src/System.Diagnostics.Contracts.csproj
@@ -18,8 +18,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj b/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
index b498839d5f87..eb14bcba806f 100644
--- a/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
+++ b/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
@@ -7,7 +7,7 @@
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <DocumentationFile>$(OutputPath)$(AssemblyName).xml</DocumentationFile>
     <PackageTargetFramework>dotnet5.2</PackageTargetFramework>
-    <UseOpenKey>true</UseOpenKey>
+    <UseOpenKey Condition="'$(UseOpenKey)'==''">true</UseOpenKey>
   </PropertyGroup>
   <!-- Default configurations to help VS understand the configurations -->
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
diff --git a/src/System.Dynamic.Runtime/src/System.Dynamic.Runtime.csproj b/src/System.Dynamic.Runtime/src/System.Dynamic.Runtime.csproj
index 728835a46845..d5717d446fff 100644
--- a/src/System.Dynamic.Runtime/src/System.Dynamic.Runtime.csproj
+++ b/src/System.Dynamic.Runtime/src/System.Dynamic.Runtime.csproj
@@ -22,8 +22,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcore50aot_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
     <DefineConstants>$(DefineConstants);FEATURE_DYNAMIC_DELEGATE</DefineConstants>
   </PropertyGroup>
 
diff --git a/src/System.Globalization.Calendars/src/System.Globalization.Calendars.csproj b/src/System.Globalization.Calendars/src/System.Globalization.Calendars.csproj
index 0059772d050d..804090420de0 100644
--- a/src/System.Globalization.Calendars/src/System.Globalization.Calendars.csproj
+++ b/src/System.Globalization.Calendars/src/System.Globalization.Calendars.csproj
@@ -19,8 +19,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Globalization/src/System.Globalization.csproj b/src/System.Globalization/src/System.Globalization.csproj
index 27d7a09ae794..13f2b0fa456b 100644
--- a/src/System.Globalization/src/System.Globalization.csproj
+++ b/src/System.Globalization/src/System.Globalization.csproj
@@ -19,8 +19,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Linq.Expressions/src/System.Linq.Expressions.csproj b/src/System.Linq.Expressions/src/System.Linq.Expressions.csproj
index ae8a209b36a3..4e03c88b6870 100644
--- a/src/System.Linq.Expressions/src/System.Linq.Expressions.csproj
+++ b/src/System.Linq.Expressions/src/System.Linq.Expressions.csproj
@@ -25,8 +25,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcore50_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
     <DefineConstants>$(DefineConstants);FEATURE_DYNAMIC_DELEGATE</DefineConstants>
   </PropertyGroup>
   <ItemGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
diff --git a/src/System.Net.Http.WinHttpHandler/tests/UnitTests/System.Net.Http.WinHttpHandler.Unit.Tests.csproj b/src/System.Net.Http.WinHttpHandler/tests/UnitTests/System.Net.Http.WinHttpHandler.Unit.Tests.csproj
index 46fcf0fed60e..0d63b1db9039 100644
--- a/src/System.Net.Http.WinHttpHandler/tests/UnitTests/System.Net.Http.WinHttpHandler.Unit.Tests.csproj
+++ b/src/System.Net.Http.WinHttpHandler/tests/UnitTests/System.Net.Http.WinHttpHandler.Unit.Tests.csproj
@@ -11,7 +11,7 @@
     <OutputType>Library</OutputType>
     <AssemblyName>System.Net.Http.WinHttpHandler.Unit.Tests</AssemblyName>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
     <UnsupportedPlatforms>Linux;OSX;FreeBSD</UnsupportedPlatforms>
   </PropertyGroup>
   
diff --git a/src/System.Net.Http/tests/UnitTests/System.Net.Http.Unit.Tests.csproj b/src/System.Net.Http/tests/UnitTests/System.Net.Http.Unit.Tests.csproj
index ea3df8ff5c9c..63792bf9d405 100644
--- a/src/System.Net.Http/tests/UnitTests/System.Net.Http.Unit.Tests.csproj
+++ b/src/System.Net.Http/tests/UnitTests/System.Net.Http.Unit.Tests.csproj
@@ -11,7 +11,7 @@
     <OutputType>Library</OutputType>
     <RootNamespace>System.Net.Http.Unit.Tests</RootNamespace>
     <AssemblyName>System.Net.Http.Unit.Tests</AssemblyName>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   
diff --git a/src/System.Net.NameResolution/tests/PalTests/System.Net.NameResolution.Pal.Tests.csproj b/src/System.Net.NameResolution/tests/PalTests/System.Net.NameResolution.Pal.Tests.csproj
index bd63c56e0bfa..b50c03e99047 100644
--- a/src/System.Net.NameResolution/tests/PalTests/System.Net.NameResolution.Pal.Tests.csproj
+++ b/src/System.Net.NameResolution/tests/PalTests/System.Net.NameResolution.Pal.Tests.csproj
@@ -9,7 +9,7 @@
     <OutputType>Library</OutputType>
     <ProjectGuid>{F6D1C093-081D-46DE-B5A8-516533375FDD}</ProjectGuid>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
     <UnsupportedPlatforms>FreeBSD</UnsupportedPlatforms>
   </PropertyGroup>
   
diff --git a/src/System.Net.NetworkInformation/tests/FunctionalTests/System.Net.NetworkInformation.Functional.Tests.csproj b/src/System.Net.NetworkInformation/tests/FunctionalTests/System.Net.NetworkInformation.Functional.Tests.csproj
index 84c6181c33f0..a4137d6b9f7b 100644
--- a/src/System.Net.NetworkInformation/tests/FunctionalTests/System.Net.NetworkInformation.Functional.Tests.csproj
+++ b/src/System.Net.NetworkInformation/tests/FunctionalTests/System.Net.NetworkInformation.Functional.Tests.csproj
@@ -10,7 +10,7 @@
     <ProjectGuid>{DCBB8805-4658-44BF-B5E8-B6714EC8936B}</ProjectGuid>
     <OutputType>Library</OutputType>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <ResourcesSourceOutputDirectory>..\..\src\Resources\</ResourcesSourceOutputDirectory>
+    <ResourcesSourceOutputDirectory>../../src/Resources/</ResourcesSourceOutputDirectory>
   </PropertyGroup>
   <!-- Help VS understand available configurations -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'" />
diff --git a/src/System.Net.NetworkInformation/tests/UnitTests/System.Net.NetworkInformation.WinRT.Unit.Tests.csproj b/src/System.Net.NetworkInformation/tests/UnitTests/System.Net.NetworkInformation.WinRT.Unit.Tests.csproj
index bbc7831fc053..0b60181d0978 100644
--- a/src/System.Net.NetworkInformation/tests/UnitTests/System.Net.NetworkInformation.WinRT.Unit.Tests.csproj
+++ b/src/System.Net.NetworkInformation/tests/UnitTests/System.Net.NetworkInformation.WinRT.Unit.Tests.csproj
@@ -9,7 +9,7 @@
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProjectGuid>{2194D6A2-1A35-46B5-8233-AEEBCBD31EF9}</ProjectGuid>
     <OutputType>Library</OutputType>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
   </PropertyGroup>
   <!-- Help VS understand available configurations -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'" />
diff --git a/src/System.Net.Primitives/tests/PalTests/System.Net.Primitives.Pal.Tests.csproj b/src/System.Net.Primitives/tests/PalTests/System.Net.Primitives.Pal.Tests.csproj
index b84c2cbb4ec0..a5722b0e2c66 100644
--- a/src/System.Net.Primitives/tests/PalTests/System.Net.Primitives.Pal.Tests.csproj
+++ b/src/System.Net.Primitives/tests/PalTests/System.Net.Primitives.Pal.Tests.csproj
@@ -11,7 +11,7 @@
     <OutputType>Library</OutputType>
     <ProjectGuid>{7860A11A-1841-4416-8A30-28EEEB42C6BB}</ProjectGuid>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
   </PropertyGroup>
   
   <!-- Help VS understand available configurations -->
diff --git a/src/System.Net.Primitives/tests/UnitTests/System.Net.Primitives.UnitTests.Tests.csproj b/src/System.Net.Primitives/tests/UnitTests/System.Net.Primitives.UnitTests.Tests.csproj
index 18b59c894eb1..5390005e1a97 100644
--- a/src/System.Net.Primitives/tests/UnitTests/System.Net.Primitives.UnitTests.Tests.csproj
+++ b/src/System.Net.Primitives/tests/UnitTests/System.Net.Primitives.UnitTests.Tests.csproj
@@ -11,7 +11,7 @@
     <ProjectGuid>{FCFF9C63-CE7A-476E-8241-7B7236FFDBFB}</ProjectGuid>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>169,649</NoWarn>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
   </PropertyGroup>
   <!-- Help VS understand available configurations -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Linux_Debug|AnyCPU'" />
diff --git a/src/System.Net.Requests/tests/System.Net.Requests.Tests.csproj b/src/System.Net.Requests/tests/System.Net.Requests.Tests.csproj
index 4809e4d7ab5d..2c1a01bcdd61 100644
--- a/src/System.Net.Requests/tests/System.Net.Requests.Tests.csproj
+++ b/src/System.Net.Requests/tests/System.Net.Requests.Tests.csproj
@@ -9,7 +9,7 @@
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProjectGuid>{851A40FE-7F07-415D-8592-5FE2096E84D3}</ProjectGuid>
     <OutputType>Library</OutputType>
-    <StringResourcesPath>..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../src/Resources/Strings.resx</StringResourcesPath>
   </PropertyGroup>
   
   <!-- Help VS understand available configurations -->
diff --git a/src/System.Net.Security/src/System.Net.Security.csproj b/src/System.Net.Security/src/System.Net.Security.csproj
index 812c8005b5aa..3c6b07a3c388 100644
--- a/src/System.Net.Security/src/System.Net.Security.csproj
+++ b/src/System.Net.Security/src/System.Net.Security.csproj
@@ -15,12 +15,12 @@
     <UsePackageTargetRuntimeDefaults>true</UsePackageTargetRuntimeDefaults>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetsWindows)' == 'true' and '$(ProjectJson)' == '' ">
-    <ProjectJson>win\project.json</ProjectJson>
-    <ProjectLockJson>win\project.lock.json</ProjectLockJson>
+    <ProjectJson>win/project.json</ProjectJson>
+    <ProjectLockJson>win/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetsUnix)' == 'true' and '$(ProjectJson)' == '' ">
-    <ProjectJson>unix\project.json</ProjectJson>
-    <ProjectLockJson>unix\project.lock.json</ProjectLockJson>
+    <ProjectJson>unix/project.json</ProjectJson>
+    <ProjectLockJson>unix/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <!-- Help VS understand available configurations -->
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Linux_Debug|AnyCPU' " />
diff --git a/src/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj b/src/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj
index 2beb4135476c..9e3bfb78ded7 100644
--- a/src/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj
+++ b/src/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj
@@ -12,12 +12,12 @@
   </PropertyGroup>
   
   <PropertyGroup Condition=" '$(TargetsWindows)' == 'true' and '$(ProjectJson)' == '' ">
-    <ProjectJson>win\project.json</ProjectJson>
-    <ProjectLockJson>win\project.lock.json</ProjectLockJson>
+    <ProjectJson>win/project.json</ProjectJson>
+    <ProjectLockJson>win/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetsUnix)' == 'true' and '$(ProjectJson)' == '' ">
-    <ProjectJson>unix\project.json</ProjectJson>
-    <ProjectLockJson>unix\project.lock.json</ProjectLockJson>
+    <ProjectJson>unix/project.json</ProjectJson>
+    <ProjectLockJson>unix/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   
   <!-- Help VS understand available configurations -->
diff --git a/src/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj b/src/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj
index 0b4934414af8..0a40abe05365 100644
--- a/src/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj
+++ b/src/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj
@@ -9,7 +9,7 @@
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProjectGuid>{0D174EA9-9E61-4519-8D31-7BD2331A1982}</ProjectGuid>
     <OutputType>Library</OutputType>
-    <StringResourcesPath>..\..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../../src/Resources/Strings.resx</StringResourcesPath>
   </PropertyGroup>
   <!-- Help VS understand available configurations -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'" />
diff --git a/src/System.Net.WebSockets.Client/tests/System.Net.WebSockets.Client.Tests.csproj b/src/System.Net.WebSockets.Client/tests/System.Net.WebSockets.Client.Tests.csproj
index 8091116df907..32aac3abf3c6 100644
--- a/src/System.Net.WebSockets.Client/tests/System.Net.WebSockets.Client.Tests.csproj
+++ b/src/System.Net.WebSockets.Client/tests/System.Net.WebSockets.Client.Tests.csproj
@@ -9,7 +9,7 @@
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProjectGuid>{7C395A91-D955-444C-98BF-D3F809A56CE1}</ProjectGuid>
     <OutputType>Library</OutputType>
-    <StringResourcesPath>..\src\Resources\Strings.resx</StringResourcesPath>
+    <StringResourcesPath>../src/Resources/Strings.resx</StringResourcesPath>
     <UnsupportedPlatforms>Linux;OSX</UnsupportedPlatforms>
   </PropertyGroup>
 
diff --git a/src/System.Reflection.TypeExtensions/src/System.Reflection.TypeExtensions.csproj b/src/System.Reflection.TypeExtensions/src/System.Reflection.TypeExtensions.csproj
index db933ba6b3a4..e8792836a037 100644
--- a/src/System.Reflection.TypeExtensions/src/System.Reflection.TypeExtensions.csproj
+++ b/src/System.Reflection.TypeExtensions/src/System.Reflection.TypeExtensions.csproj
@@ -17,7 +17,7 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcore50aot_Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcore50aot_Release|AnyCPU'" />
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <StringResourcesPath>Resources\Strings.netcore50aot.resx</StringResourcesPath>
+    <StringResourcesPath>Resources/Strings.netcore50aot.resx</StringResourcesPath>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System\Reflection\Requires.cs" />
diff --git a/src/System.Reflection/src/System.Reflection.csproj b/src/System.Reflection/src/System.Reflection.csproj
index abdd0591f733..536da83136b4 100644
--- a/src/System.Reflection/src/System.Reflection.csproj
+++ b/src/System.Reflection/src/System.Reflection.csproj
@@ -19,8 +19,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Runtime.Serialization.Json/src/System.Runtime.Serialization.Json.csproj b/src/System.Runtime.Serialization.Json/src/System.Runtime.Serialization.Json.csproj
index e1d6f39fbefc..c88509934d4d 100644
--- a/src/System.Runtime.Serialization.Json/src/System.Runtime.Serialization.Json.csproj
+++ b/src/System.Runtime.Serialization.Json/src/System.Runtime.Serialization.Json.csproj
@@ -18,8 +18,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Runtime.Serialization.Primitives/src/System.Runtime.Serialization.Primitives.csproj b/src/System.Runtime.Serialization.Primitives/src/System.Runtime.Serialization.Primitives.csproj
index 8cf8bb58d7df..64735dac9b81 100644
--- a/src/System.Runtime.Serialization.Primitives/src/System.Runtime.Serialization.Primitives.csproj
+++ b/src/System.Runtime.Serialization.Primitives/src/System.Runtime.Serialization.Primitives.csproj
@@ -8,7 +8,6 @@
     <NoWarn>$(NoWarn);1634;1691;649</NoWarn>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <FileAlignment>512</FileAlignment>
-    <DebugSymbols>true</DebugSymbols>
     <PlatformTarget>AnyCPU</PlatformTarget>
     <ProjectGuid>{CDF0ACB5-1361-4E48-8ECB-22E8022F5F01}</ProjectGuid>
     <PackageTargetFramework Condition="'$(PackageTargetFramework)'==''">dotnet5.4</PackageTargetFramework>
diff --git a/src/System.Runtime.Serialization.Xml/src/System.Runtime.Serialization.Xml.csproj b/src/System.Runtime.Serialization.Xml/src/System.Runtime.Serialization.Xml.csproj
index d2a4d972dae6..ef3d2b9b82b9 100644
--- a/src/System.Runtime.Serialization.Xml/src/System.Runtime.Serialization.Xml.csproj
+++ b/src/System.Runtime.Serialization.Xml/src/System.Runtime.Serialization.Xml.csproj
@@ -18,8 +18,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   
   <ItemGroup Condition="'$(TargetGroup)' == 'netcore50aot'" >
diff --git a/src/System.Security.Cryptography.X509Certificates/src/System.Security.Cryptography.X509Certificates.csproj b/src/System.Security.Cryptography.X509Certificates/src/System.Security.Cryptography.X509Certificates.csproj
index a3de60b7c2f6..9bdbe01a2563 100644
--- a/src/System.Security.Cryptography.X509Certificates/src/System.Security.Cryptography.X509Certificates.csproj
+++ b/src/System.Security.Cryptography.X509Certificates/src/System.Security.Cryptography.X509Certificates.csproj
@@ -18,20 +18,20 @@
     <IsPartialFacadeAssembly Condition="'$(TargetGroup)'=='net461'">true</IsPartialFacadeAssembly>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetGroup)' == 'netcore50' and '$(ProjectJson)' == '' ">
-    <ProjectJson>netcore50\project.json</ProjectJson>
-    <ProjectLockJson>netcore50\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50/project.json</ProjectJson>
+    <ProjectLockJson>netcore50/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetGroup)' == 'net461' and '$(ProjectJson)' == '' ">
     <ProjectJson>net461\project.json</ProjectJson>
     <ProjectLockJson>net461\project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetsWindows)' == 'true' and '$(ProjectJson)' == '' ">
-    <ProjectJson>win\project.json</ProjectJson>
-    <ProjectLockJson>win\project.lock.json</ProjectLockJson>
+    <ProjectJson>win/project.json</ProjectJson>
+    <ProjectLockJson>win/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetsUnix)' == 'true' and '$(ProjectJson)' == '' ">
-    <ProjectJson>unix\project.json</ProjectJson>
-    <ProjectLockJson>unix\project.lock.json</ProjectLockJson>
+    <ProjectJson>unix/project.json</ProjectJson>
+    <ProjectLockJson>unix/project.lock.json</ProjectLockJson>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Linux_Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Linux_Release|AnyCPU'" />
diff --git a/src/System.Text.Encoding.Extensions/src/System.Text.Encoding.Extensions.csproj b/src/System.Text.Encoding.Extensions/src/System.Text.Encoding.Extensions.csproj
index f0c9879167ce..9ef805509c65 100644
--- a/src/System.Text.Encoding.Extensions/src/System.Text.Encoding.Extensions.csproj
+++ b/src/System.Text.Encoding.Extensions/src/System.Text.Encoding.Extensions.csproj
@@ -19,8 +19,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Text.Encoding/src/System.Text.Encoding.csproj b/src/System.Text.Encoding/src/System.Text.Encoding.csproj
index b33070ca522b..4f72ac45530d 100644
--- a/src/System.Text.Encoding/src/System.Text.Encoding.csproj
+++ b/src/System.Text.Encoding/src/System.Text.Encoding.csproj
@@ -19,8 +19,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj b/src/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj
index 4deb9724da99..c32ddc97adb4 100644
--- a/src/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj
+++ b/src/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj
@@ -8,7 +8,7 @@
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <PackageTargetFramework>dotnet5.1</PackageTargetFramework>
-    <UseOpenKey>true</UseOpenKey>
+    <UseOpenKey Condition="'$(UseOpenKey)'==''">true</UseOpenKey>
   </PropertyGroup>
   <!-- Default configurations to help VS understand the configurations -->
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
diff --git a/src/System.Threading.Tasks.Extensions/src/System.Threading.Tasks.Extensions.csproj b/src/System.Threading.Tasks.Extensions/src/System.Threading.Tasks.Extensions.csproj
index 70cbfbf64e20..d3d2d136b6bf 100644
--- a/src/System.Threading.Tasks.Extensions/src/System.Threading.Tasks.Extensions.csproj
+++ b/src/System.Threading.Tasks.Extensions/src/System.Threading.Tasks.Extensions.csproj
@@ -7,7 +7,7 @@
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <DocumentationFile>$(OutputPath)$(AssemblyName).xml</DocumentationFile>
     <PackageTargetFramework>dotnet5.1</PackageTargetFramework>
-    <UseOpenKey>true</UseOpenKey>
+    <UseOpenKey Condition="'$(UseOpenKey)'==''">true</UseOpenKey>
   </PropertyGroup>
   <!-- Default configurations to help VS understand the configurations -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'" />
diff --git a/src/System.Threading.Timer/src/System.Threading.Timer.csproj b/src/System.Threading.Timer/src/System.Threading.Timer.csproj
index c389d26623b7..82b9b7d5678f 100644
--- a/src/System.Threading.Timer/src/System.Threading.Timer.csproj
+++ b/src/System.Threading.Timer/src/System.Threading.Timer.csproj
@@ -19,8 +19,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net46_Release|AnyCPU'" />
 
   <PropertyGroup Condition="'$(TargetGroup)' == 'netcore50aot'">
-    <ProjectJson>netcore50aot\project.json</ProjectJson>
-    <ProjectLockJson>netcore50aot\project.lock.json</ProjectLockJson>
+    <ProjectJson>netcore50aot/project.json</ProjectJson>
+    <ProjectLockJson>netcore50aot/project.lock.json</ProjectLockJson>
   </PropertyGroup>
 
   <ItemGroup>