diff --git a/Directory.Build.props b/Directory.Build.props
index f149734c7c81f4..0983ba4ae36f89 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -245,6 +245,7 @@
     <CoreLibSharedDir>$([MSBuild]::NormalizeDirectory('$(LibrariesProjectRoot)', 'System.Private.CoreLib', 'src'))</CoreLibSharedDir>
     <CoreLibProject Condition="'$(RuntimeFlavor)' == 'CoreCLR'">$([MSBuild]::NormalizePath('$(CoreClrProjectRoot)', 'System.Private.CoreLib', 'System.Private.CoreLib.csproj'))</CoreLibProject>
     <CoreLibProject Condition="'$(RuntimeFlavor)' == 'Mono'">$([MSBuild]::NormalizePath('$(MonoProjectRoot)', 'System.Private.CoreLib', 'System.Private.CoreLib.csproj'))</CoreLibProject>
+    <CoreLibProject Condition="'$(UseNativeAotCoreLib)' == 'true'">$([MSBuild]::NormalizePath('$(CoreClrProjectRoot)', 'nativeaot', 'System.Private.CoreLib', 'src', 'System.Private.CoreLib.csproj'))</CoreLibProject>
 
     <!-- this property is used by the SDK to pull in mono-based runtime packs -->
     <UseMonoRuntime Condition="'$(UseMonoRuntime)' == '' and '$(RuntimeFlavor)' == 'Mono'">true</UseMonoRuntime>
diff --git a/eng/ApiCompatExcludeAttributes.txt b/eng/ApiCompatExcludeAttributes.txt
index 19475f50297f8a..5ea702ad6f3d4a 100644
--- a/eng/ApiCompatExcludeAttributes.txt
+++ b/eng/ApiCompatExcludeAttributes.txt
@@ -1,3 +1,5 @@
 T:System.CLSCompliantAttribute
 T:System.Diagnostics.CodeAnalysis.MemberNotNullAttribute
 T:System.Diagnostics.CodeAnalysis.RequiresDynamicCodeAttribute
+T:System.Diagnostics.DebuggerGuidedStepThroughAttribute
+T:System.Runtime.CompilerServices.EagerStaticClassConstructionAttribute
diff --git a/eng/Subsets.props b/eng/Subsets.props
index 22714ffc7d0a88..d8aa6d9fea0fea 100644
--- a/eng/Subsets.props
+++ b/eng/Subsets.props
@@ -49,9 +49,12 @@
     <RuntimeFlavor Condition="'$(RuntimeFlavor)' == ''">$(PrimaryRuntimeFlavor)</RuntimeFlavor>
   </PropertyGroup>
 
-  <!-- CLR NativeAot only builds in a subset of the matrix -->
   <PropertyGroup>
+    <!-- CLR NativeAot only builds in a subset of the matrix -->
     <NativeAotSupported Condition="('$(TargetOS)' == 'windows' or '$(TargetOS)' == 'linux' or '$(TargetOS)' == 'OSX') and ('$(TargetArchitecture)' == 'x64' or '$(TargetArchitecture)' == 'arm64') and ('$(TargetOS)' != 'OSX' or '$(TargetArchitecture)' != 'arm64') and ('$(__DistroRid)' != 'linux-musl-arm64')">true</NativeAotSupported>
+
+    <!-- If we're building clr.nativeaotlibs and not building the CLR runtime, compile libraries against NativeAOT CoreLib -->
+    <UseNativeAotCoreLib Condition="$(_subset.Contains('+clr.nativeaotlibs+')) and !$(_subset.Contains('+clr+')) and !$(_subset.Contains('+clr.runtime+'))">true</UseNativeAotCoreLib>
   </PropertyGroup>
 
   <PropertyGroup>
diff --git a/src/libraries/System.Reflection/src/MatchingRefApiCompatBaseline.txt b/src/libraries/System.Reflection/src/MatchingRefApiCompatBaseline.txt
index 47ffa8392dfb7b..93972536f0210c 100644
--- a/src/libraries/System.Reflection/src/MatchingRefApiCompatBaseline.txt
+++ b/src/libraries/System.Reflection/src/MatchingRefApiCompatBaseline.txt
@@ -1,3 +1,6 @@
 Compat issues with assembly System.Reflection:
 MembersMustExist : Member 'protected System.ModuleHandle System.Reflection.Module.GetModuleHandleImpl()' does not exist in the reference but it does exist in the implementation.
-Total Issues: 1
+MembersMustExist : Member 'public System.Reflection.ParameterInfo[] System.Reflection.MethodBase.GetParametersNoCopy()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.Reflection.MethodBase System.Reflection.MethodBase.MetadataDefinitionMethod.get()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.Int32 System.Reflection.MethodInfo.GenericParameterCount.get()' does not exist in the reference but it does exist in the implementation.
+Total Issues: 4
diff --git a/src/libraries/System.Runtime/src/MatchingRefApiCompatBaseline.txt b/src/libraries/System.Runtime/src/MatchingRefApiCompatBaseline.txt
index cbe8cabdbb2956..6c58cd1642bf78 100644
--- a/src/libraries/System.Runtime/src/MatchingRefApiCompatBaseline.txt
+++ b/src/libraries/System.Runtime/src/MatchingRefApiCompatBaseline.txt
@@ -24,4 +24,13 @@ CannotMakeMemberAbstract : Member 'public System.Boolean System.IO.FileSystemInf
 CannotMakeMemberAbstract : Member 'public System.String System.IO.FileSystemInfo.Name.get()' is abstract in the reference but is not abstract in the implementation.
 # C# generates backing fields for fixed buffers as public.
 TypesMustExist : Type 'System.IO.Enumeration.FileSystemEntry.<_fileNameBuffer>e__FixedBuffer' does not exist in the reference but it does exist in the implementation.
-
+MembersMustExist : Member 'public void System.ModuleHandle..ctor(System.Reflection.Module)' does not exist in the reference but it does exist in the implementation.
+CannotRemoveBaseTypeOrInterface : Type 'System.RuntimeTypeHandle' does not implement interface 'System.IEquatable<System.RuntimeTypeHandle>' in the reference but it does in the implementation.
+MembersMustExist : Member 'public System.String System.String System.Type.DefaultTypeNameWhenMissingMetadata' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.String System.Type.FormatTypeNameForReflection()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.String System.Type.InternalGetNameIfAvailable(System.Type)' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.String System.Type.InternalNameIfAvailable.get()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.Boolean System.TypedReference.IsNull.get()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.Reflection.ParameterInfo[] System.Reflection.MethodBase.GetParametersNoCopy()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.Reflection.MethodBase System.Reflection.MethodBase.MetadataDefinitionMethod.get()' does not exist in the reference but it does exist in the implementation.
+MembersMustExist : Member 'public System.Int32 System.Reflection.MethodInfo.GenericParameterCount.get()' does not exist in the reference but it does exist in the implementation.