diff --git a/eng/Subsets.props b/eng/Subsets.props
index 4af6e90f9172b..9e35431728e24 100644
--- a/eng/Subsets.props
+++ b/eng/Subsets.props
@@ -107,6 +107,7 @@
   <PropertyGroup>
     <!-- CLR NativeAot only builds in a subset of the matrix -->
     <NativeAotSupported Condition="('$(TargetOS)' == 'windows' or '$(TargetOS)' == 'linux' or '$(TargetOS)' == 'osx' or '$(TargetOS)' == 'maccatalyst' or '$(TargetOS)' == 'iossimulator' or '$(TargetOS)' == 'ios' or '$(TargetOS)' == 'tvossimulator' or '$(TargetOS)' == 'tvos' or '$(TargetOS)' == 'freebsd') and ('$(TargetArchitecture)' == 'x64' or '$(TargetArchitecture)' == 'arm64')">true</NativeAotSupported>
+    <Crossgen2Supported Condition="'$(TargetArchitecture)' != 'loongarch64'">true</Crossgen2Supported>
 
     <!-- If we're building clr.nativeaotlibs and not building the CLR runtime, compile libraries against NativeAOT CoreLib -->
     <UseNativeAotCoreLib Condition="'$(TestNativeAot)' == 'true' or ($(_subset.Contains('+clr.nativeaotlibs+')) and !$(_subset.Contains('+clr.native+')) and !$(_subset.Contains('+clr.runtime+')))">true</UseNativeAotCoreLib>
@@ -365,7 +366,7 @@
       Test="true" Category="tools"/>
   </ItemGroup>
 
-  <ItemGroup Condition="$(_subset.Contains('+clr.nativecorelib+'))">
+  <ItemGroup Condition="$(_subset.Contains('+clr.nativecorelib+')) and '$(Crossgen2Supported)' == 'true'">
     <!-- Build crossgen2 that will be used to compile System.Private.CoreLib library for CoreCLR -->
     <ProjectToBuild Condition="('$(CrossBuild)' == 'true' or '$(BuildArchitecture)' != '$(TargetArchitecture)') and '$(BuildArchitecture)' == 'x64'" Include="$(CoreClrProjectRoot)tools\aot\crossgen2\crossgen2_crossarch.csproj" Category="clr" />
     <ProjectToBuild Condition="!(('$(CrossBuild)' == 'true' or '$(BuildArchitecture)' != '$(TargetArchitecture)') and '$(BuildArchitecture)' == 'x64')" Include="$(CoreClrProjectRoot)tools\aot\crossgen2\crossgen2.csproj" Category="clr" />
diff --git a/src/coreclr/crossgen-corelib.proj b/src/coreclr/crossgen-corelib.proj
index 5ba72f0af24c2..62022ee542eab 100644
--- a/src/coreclr/crossgen-corelib.proj
+++ b/src/coreclr/crossgen-corelib.proj
@@ -16,7 +16,7 @@
       <CrossDir Condition="'$(CrossBuild)' == 'true' or '$(BuildArchitecture)' != '$(TargetArchitecture)'">$(BuildArchitecture)</CrossDir>
 
       <BuildDll>true</BuildDll>
-      <BuildDll Condition="'$(TargetArchitecture)' == 'riscv64'">false</BuildDll>
+      <BuildDll Condition="'$(TargetArchitecture)' == 'riscv64' or '$(TargetArchitecture)' == 'loongarch64'">false</BuildDll>
 
       <BuildPdb>false</BuildPdb>
       <BuildPdb Condition="$(BuildDll) and '$(OS)' == 'Windows_NT' and '$(TargetOS)' == 'windows'">true</BuildPdb>
diff --git a/src/libraries/tests.proj b/src/libraries/tests.proj
index 49751adfb7ecc..a631ef940cd4f 100644
--- a/src/libraries/tests.proj
+++ b/src/libraries/tests.proj
@@ -329,6 +329,12 @@
   <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(RunDisabledWasmTests)' != 'true' and '$(RunAOTCompilation)' != 'true'">
   </ItemGroup>
 
+  <ItemGroup Condition="$(TargetArchitecture) == 'loongarch64'">
+    <!-- https://github.com/dotnet/roslyn/issues/65597. -->
+    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Runtime.InteropServices.JavaScript\gen\JSImportGenerator\JSImportGenerator.csproj" />
+    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Runtime.InteropServices.JavaScript\src\System.Runtime.InteropServices.JavaScript.csproj" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(RunDisabledWasmTests)' != 'true'">
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)Microsoft.NETCore.Platforms\tests\Microsoft.NETCore.Platforms.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Runtime.InteropServices.JavaScript\tests\JSImportGenerator.UnitTest\JSImportGenerator.Unit.Tests.csproj" />
diff --git a/src/tests/build.proj b/src/tests/build.proj
index 8a00ffa945fe0..2288176987927 100644
--- a/src/tests/build.proj
+++ b/src/tests/build.proj
@@ -9,6 +9,7 @@
     <MSBuildEnableAllPropertyFunctions>1</MSBuildEnableAllPropertyFunctions>
     <Language>C#</Language>
     <RuntimeIdentifier>$(OutputRid)</RuntimeIdentifier>
+    <RestoreAdditionalProjectSources Condition="$(TargetArchitecture) == 'loongarch64'">$(RestoreAdditionalProjectSources);$(ArtifactsPackagesDir)</RestoreAdditionalProjectSources>
   </PropertyGroup>
 
   <ItemGroup>
@@ -435,6 +436,7 @@
   <Target Name="RestorePackage">
     <PropertyGroup>
       <_ConfigurationProperties>/p:TargetOS=$(TargetOS) /p:TargetArchitecture=$(TargetArchitecture) /p:Configuration=$(Configuration) /p:CrossBuild=$(CrossBuild)</_ConfigurationProperties>
+      <_ConfigurationProperties Condition="$(TargetArchitecture) == 'loongarch64'">$(_ConfigurationProperties) /p:RestoreAdditionalProjectSources=$(ArtifactsPackagesDir)</_ConfigurationProperties>
       <DotnetRestoreCommand Condition="'$(__DistroRid)' == ''">"$(DotNetTool)" restore $(RestoreProj) $(PackageVersionArg) /p:SetTFMForRestore=true $(_ConfigurationProperties)</DotnetRestoreCommand>
       <DotnetRestoreCommand Condition="'$(__DistroRid)' != ''">"$(DotNetTool)" restore -r $(__DistroRid) $(RestoreProj) $(PackageVersionArg) /p:SetTFMForRestore=true $(_ConfigurationProperties)</DotnetRestoreCommand>
     </PropertyGroup>