diff --git a/src/libraries/shims/src/mscorlib.csproj b/src/libraries/shims/src/mscorlib.csproj
index 718cd1a3f1812..dd9d0fe6105c2 100644
--- a/src/libraries/shims/src/mscorlib.csproj
+++ b/src/libraries/shims/src/mscorlib.csproj
@@ -7,4 +7,10 @@
   <ItemGroup>
     <Compile Include="mscorlib.forwards.cs" />
   </ItemGroup>
+  <Target Name="RemoveConflictingAssemblyReference" AfterTargets="FindReferenceAssembliesForReferences">
+    <ItemGroup>
+      <!-- System.Collections.Generic.CollectionExtensions type exists in both System.Private.CoreLib and Microsoft.Extensions.DependencyModel, we only want the former -->
+      <ReferencePathWithRefAssemblies Remove="@(ReferencePathWithRefAssemblies->WithMetadataValue('Filename', 'Microsoft.Extensions.DependencyModel'))" />
+    </ItemGroup>
+  </Target>
 </Project>
diff --git a/src/libraries/shims/src/mscorlib.forwards.cs b/src/libraries/shims/src/mscorlib.forwards.cs
index 5598f5bf8f24d..76b4543852a3d 100644
--- a/src/libraries/shims/src/mscorlib.forwards.cs
+++ b/src/libraries/shims/src/mscorlib.forwards.cs
@@ -19,6 +19,95 @@
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.OrdinalComparer))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.UnitySerializationHolder))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.Contracts.ContractException))]
-// This is required for back-compatibility with legacy Xamarin which had Stack<T> and Queue<T> in mscorlib
-[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.Stack<>))]
+// This is required for back-compatibility with legacy Xamarin which had Stack<T> and Queue<T> in mscorlib and also added a few NS2.1 types that didn't exist in .NET Framework
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.HashCode))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IAsyncDisposable))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Index))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.MathF))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.MemoryExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Memory<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Range))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.ReadOnlyMemory<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.ReadOnlySpan<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.SequencePosition))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Span<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.ArrayBufferWriter<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.ArrayPool<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.BuffersExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.IBufferWriter<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.IMemoryOwner<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.IPinnable))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.MemoryHandle))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.MemoryManager<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.MemoryPool<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.OperationStatus))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.ReadOnlySequenceSegment<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.ReadOnlySequence<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.ReadOnlySpanAction<,>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.SequenceReaderExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.SequenceReader<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.SpanAction<,>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.StandardFormat))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.Binary.BinaryPrimitives))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.Text.Base64))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.Text.Utf8Formatter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Buffers.Text.Utf8Parser))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.CollectionExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.IAsyncEnumerable<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.IAsyncEnumerator<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.KeyValuePair))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.Queue<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Collections.Generic.Stack<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.AllowNullAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.DisallowNullAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.DoesNotReturnAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.DoesNotReturnIfAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.MaybeNullAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.NotNullAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.NotNullWhenAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.Tracing.DiagnosticCounter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.Tracing.EventCounter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.Tracing.IncrementingEventCounter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.Tracing.IncrementingPollingCounter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Diagnostics.Tracing.PollingCounter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Globalization.ISOWeek))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.EnumerationOptions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.MatchCasing))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.MatchType))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.Enumeration.FileSystemEntry))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.Enumeration.FileSystemEnumerable<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.Enumeration.FileSystemEnumerator<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IO.Enumeration.FileSystemName))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Numerics.Vector))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Numerics.Vector<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.AssemblyExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.EventInfoExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.MemberInfoExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.MethodInfoExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.ModuleExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.PropertyInfoExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Reflection.TypeExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.AsyncIteratorMethodBuilder))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.AsyncIteratorStateMachineAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.AsyncMethodBuilderAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.ConfiguredAsyncDisposable))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.EnumeratorCancellationAttribute))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.ValueTaskAwaiter))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.CompilerServices.ValueTaskAwaiter<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.InteropServices.MemoryMarshal))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Runtime.InteropServices.SequenceMarshal))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.TaskAsyncEnumerableExtensions))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.ValueTask))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.ValueTask<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.Sources.IValueTaskSource))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.Sources.IValueTaskSource<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<>))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.Sources.ValueTaskSourceOnCompletedFlags))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Threading.Tasks.Sources.ValueTaskSourceStatus))]