diff --git a/eng/SourceBuildPrebuiltBaseline.xml b/eng/SourceBuildPrebuiltBaseline.xml
index 592d3954059e8..8451ebe80c273 100644
--- a/eng/SourceBuildPrebuiltBaseline.xml
+++ b/eng/SourceBuildPrebuiltBaseline.xml
@@ -13,13 +13,15 @@
     <UsagePattern IdentityGlob="Microsoft.CodeAnalysis.VisualBasic.CodeStyle/*" />
     <UsagePattern IdentityGlob="Microsoft.Net.Compilers.Toolset/*" />
 
-    <!-- Roslyn's source-build CI builds both NetPrevious and NetCurrent. This 7.0 ref pack shows up as
+    <!-- Roslyn's source-build CI builds both NetPrevious and NetCurrent. This 7.0 / 8.0 ref pack shows up as
          prebuilt only for the repo CI build but not full source-build. -->
     <UsagePattern IdentityGlob="Microsoft.AspNetCore.App.Ref/7.0*" />
+    <UsagePattern IdentityGlob="Microsoft.AspNetCore.App.Ref/8.0*" />
 
-    <!-- Roslyn's source-build CI builds both NetPrevious and NetCurrent. This 7.0 ref pack shows up as
+    <!-- Roslyn's source-build CI builds both NetPrevious and NetCurrent. This 7.0 / 8.0 ref pack shows up as
          prebuilt only for the repo CI build but not full source-build. -->
     <UsagePattern IdentityGlob="Microsoft.NETCore.App.Ref/7.0*" />
+    <UsagePattern IdentityGlob="Microsoft.NETCore.App.Ref/8.0*" />
 
      <!-- This is upgraded to latest version in full source-build and can be baselined for repo build -->
     <UsagePattern IdentityGlob="Microsoft.Extensions.Configuration*/8.0*" />
diff --git a/src/Compilers/CSharp/Test/Emit2/Emit/LocalStateTracing/LocalStateTracingTests.cs b/src/Compilers/CSharp/Test/Emit2/Emit/LocalStateTracing/LocalStateTracingTests.cs
index 4315771543ce5..000ddcb8d0bce 100644
--- a/src/Compilers/CSharp/Test/Emit2/Emit/LocalStateTracing/LocalStateTracingTests.cs
+++ b/src/Compilers/CSharp/Test/Emit2/Emit/LocalStateTracing/LocalStateTracingTests.cs
@@ -5520,7 +5520,7 @@ static void Main()
 Main: Entered
 Main: L'a' = 1
 Main: L'b' = 2
-Main: L4 = System.Linq.Enumerable+SelectArrayIterator`2[System.Int32,System.Int32]
+Main: L4 = System.Linq.Enumerable+ArraySelectIterator`2[System.Int32,System.Int32]
 Main: Entered lambda '<Main>b__0'
 <Main>b__0: P'item'[0] = 10
 <Main>b__0: Returned
diff --git a/src/Features/CSharpTest/Microsoft.CodeAnalysis.CSharp.Features.UnitTests.csproj b/src/Features/CSharpTest/Microsoft.CodeAnalysis.CSharp.Features.UnitTests.csproj
index 801b6a5a0c0e4..73c7105b1f10e 100644
--- a/src/Features/CSharpTest/Microsoft.CodeAnalysis.CSharp.Features.UnitTests.csproj
+++ b/src/Features/CSharpTest/Microsoft.CodeAnalysis.CSharp.Features.UnitTests.csproj
@@ -3,7 +3,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Library</OutputType>
-    <TargetFrameworks>$(NetRoslyn);net472</TargetFrameworks>
+    <TargetFrameworks>$(NetRoslynNext);net472</TargetFrameworks>
     <RootNamespace>Microsoft.CodeAnalysis.CSharp.UnitTests</RootNamespace>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
diff --git a/src/Features/CSharpTest/SemanticSearch/CSharpSemanticSearchServiceTests.cs b/src/Features/CSharpTest/SemanticSearch/CSharpSemanticSearchServiceTests.cs
index 02d2a79a8fc74..c841e11de33b6 100644
--- a/src/Features/CSharpTest/SemanticSearch/CSharpSemanticSearchServiceTests.cs
+++ b/src/Features/CSharpTest/SemanticSearch/CSharpSemanticSearchServiceTests.cs
@@ -240,7 +240,7 @@ static ISymbol F(ISymbol s)
         AssertEx.Equal(
             $"   at Program.<<Main>$>g__F|0_1(ISymbol s) in {FeaturesResources.Query}:line 11" + Environment.NewLine +
             $"   at Program.<>c.<<Main>$>b__0_2(ISymbol x) in {FeaturesResources.Query}:line 5" + Environment.NewLine +
-            $"   at System.Linq.Enumerable.SelectArrayIterator`2.MoveNext()" + Environment.NewLine,
+            $"   at System.Linq.Enumerable.ArraySelectIterator`2.MoveNext()" + Environment.NewLine,
             exception.StackTrace.JoinText());
     }
 }
diff --git a/src/Scripting/CSharpTest/CommandLineRunnerTests.cs b/src/Scripting/CSharpTest/CommandLineRunnerTests.cs
index 0d50eb1e902cc..5a3295f2c3511 100644
--- a/src/Scripting/CSharpTest/CommandLineRunnerTests.cs
+++ b/src/Scripting/CSharpTest/CommandLineRunnerTests.cs
@@ -133,7 +133,7 @@ select x * x
 > from x in await GetStuffAsync()
 . where x > 2
 . select x * x
-Enumerable.WhereSelectArrayIterator<int, int> {{ 9, 16, 25 }}
+Enumerable.ArrayWhereSelectIterator<int, int> {{ 9, 16, 25 }}
 > ", runner.Console.Out.ToString());
 
             AssertEx.AssertEqualToleratingWhitespaceDifferences(
diff --git a/src/Scripting/CSharpTest/Microsoft.CodeAnalysis.CSharp.Scripting.UnitTests.csproj b/src/Scripting/CSharpTest/Microsoft.CodeAnalysis.CSharp.Scripting.UnitTests.csproj
index 5e8ced49b9982..3c7a527a29e20 100644
--- a/src/Scripting/CSharpTest/Microsoft.CodeAnalysis.CSharp.Scripting.UnitTests.csproj
+++ b/src/Scripting/CSharpTest/Microsoft.CodeAnalysis.CSharp.Scripting.UnitTests.csproj
@@ -5,7 +5,7 @@
     <OutputType>Library</OutputType>
     <RootNamespace>Microsoft.CodeAnalysis.CSharp.Scripting.UnitTests</RootNamespace>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <TargetFrameworks>$(NetRoslyn);net472</TargetFrameworks>
+    <TargetFrameworks>$(NetRoslynNext);net472</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\..\Compilers\Core\Portable\Microsoft.CodeAnalysis.csproj" />
diff --git a/src/Scripting/CSharpTest/ObjectFormatterTests.cs b/src/Scripting/CSharpTest/ObjectFormatterTests.cs
index b4ce5c4f787f5..d0e7b7fc2c0e2 100644
--- a/src/Scripting/CSharpTest/ObjectFormatterTests.cs
+++ b/src/Scripting/CSharpTest/ObjectFormatterTests.cs
@@ -507,7 +507,7 @@ public void DebuggerProxy_FrameworkTypes_IEnumerable_Exception()
                 return i < 7;
             });
             str = s_formatter.FormatObject(obj, SingleLineOptions);
-            Assert.Equal("Enumerable.WhereEnumerableIterator<int> { 0, 1, 2, 3, 4, !<Exception> ... }", str);
+            Assert.Equal("Enumerable.IEnumerableWhereIterator<int> { 0, 1, 2, 3, 4, !<Exception> ... }", str);
         }
 
         [Fact]
diff --git a/src/Tools/BuildBoss/ProjectCheckerUtil.cs b/src/Tools/BuildBoss/ProjectCheckerUtil.cs
index 30169fa97809f..f42d30b8e6ace 100644
--- a/src/Tools/BuildBoss/ProjectCheckerUtil.cs
+++ b/src/Tools/BuildBoss/ProjectCheckerUtil.cs
@@ -247,6 +247,7 @@ private bool CheckTargetFrameworks(TextWriter textWriter)
                     case "net472":
                     case "netstandard2.0":
                     case "$(NetRoslyn)":
+                    case "$(NetRoslynNext)":
                     case "$(NetRoslynSourceBuild)":
                     case "$(NetRoslynToolset)":
                     case "$(NetRoslynAll)":