diff --git a/Mono.TextTemplating.Build/Mono.TextTemplating.Build.csproj b/Mono.TextTemplating.Build/Mono.TextTemplating.Build.csproj
index 81b90d2..9206ade 100644
--- a/Mono.TextTemplating.Build/Mono.TextTemplating.Build.csproj
+++ b/Mono.TextTemplating.Build/Mono.TextTemplating.Build.csproj
@@ -33,6 +33,7 @@
   <ItemGroup>
     <None Include="readme.md" Pack="true" PackagePath="\" />
     <ProjectReference Include="..\Mono.TextTemplating\Mono.TextTemplating.csproj" PrivateAssets="all" />
+    <ProjectReference Include="..\Mono.TextTemplating.Roslyn\Mono.TextTemplating.Roslyn.csproj" PrivateAssets="all" />
     <PackageReference Include="MessagePackAnalyzer" Version="2.5.129" PrivateAssets="all" />
     <PackageReference Include="MessagePack" Version="2.5.129" PrivateAssets="all" />
     <!-- intentionally downlevel these so they can be loaded in older VS versions -->
diff --git a/Mono.TextTemplating.Build/T4.BuildTools.targets b/Mono.TextTemplating.Build/T4.BuildTools.targets
index 3839b1b..d8c9283 100644
--- a/Mono.TextTemplating.Build/T4.BuildTools.targets
+++ b/Mono.TextTemplating.Build/T4.BuildTools.targets
@@ -11,6 +11,7 @@
     <UseLegacyT4Preprocessing Condition="'$(UseLegacyT4Preprocessing)'==''">False</UseLegacyT4Preprocessing>
     <TransformOnBuild Condition="'$(TransformOnBuild)'==''">False</TransformOnBuild>
     <TransformOutOfDateOnly Condition="$(TransformOutOfDateOnly)==''">true</TransformOutOfDateOnly>
+    <T4UseInProcessCompiler Condition="'$(T4UseInProcessCompiler)'==''">false</T4UseInProcessCompiler>
     <!-- legacy compat -->
     <T4DefaultNamespace Condition="'$(T4DefaultNamespace)'==''">$(PreprocessTemplateDefaultNamespace)</T4DefaultNamespace>
     <T4DefaultNamespace Condition="'$(T4DefaultNamespace)'==''">$(RootNamespace)</T4DefaultNamespace>
@@ -92,6 +93,7 @@
       IntermediateDirectory="$(_T4IntermediateTemplateOutputDir)"
       TransformOutOfDateOnly="$(TransformOutOfDateOnly)"
       PreprocessTargetRuntimeIdentifier="$(TargetFrameworkIdentifier)"
+      UseInProcessCompiler="$(T4UseInProcessCompiler)"
       >
         <Output TaskParameter="TransformTemplateOutput" ItemName="GeneratedTemplates" />
         <Output TaskParameter="PreprocessedTemplateOutput" ItemName="PreprocessedTemplates" />
diff --git a/Mono.TextTemplating.Build/T4.BuildTools.targets.buildschema.json b/Mono.TextTemplating.Build/T4.BuildTools.targets.buildschema.json
index cc8b4ad..16010ef 100644
--- a/Mono.TextTemplating.Build/T4.BuildTools.targets.buildschema.json
+++ b/Mono.TextTemplating.Build/T4.BuildTools.targets.buildschema.json
@@ -140,6 +140,11 @@
       "description": "Place preprocessed templates beside the templates instead of dynamically injecting them into the build.",
       "type": "bool"
     },
+    "T4UseInProcessCompiler": {
+      "description": "Use the in-process Roslyn compiler for T4 templates, enabling modern C# language features even when running under Visual Studio's .NET Framework MSBuild host.",
+      "type": "bool",
+      "defaultValue": "false"
+    },
     "T4Arguments": {
       "description": "Used to pass arguments when invoking on the CLI. This is a semicolon-separated list and uses the same format as encoded `T4Argument` items: `name=value`, `directive!name!value` or `processor!directive!name!value`.",
       "isList": true
diff --git a/Mono.TextTemplating.Build/TemplateBuildState.cs b/Mono.TextTemplating.Build/TemplateBuildState.cs
index 6a2a1ab..b0ca6cc 100644
--- a/Mono.TextTemplating.Build/TemplateBuildState.cs
+++ b/Mono.TextTemplating.Build/TemplateBuildState.cs
@@ -41,6 +41,8 @@ public class TemplateBuildState
 		public List<Parameter> Parameters { get; set; }
 		[Key(10)]
 		public string PreprocessTargetRuntimeIdentifier { get; set; }
+		[Key(11)]
+		public bool UseInProcessCompiler { get; set; }
 
 		internal (List<TransformTemplate> transforms, List<PreprocessedTemplate> preprocessed) GetStaleAndNewTemplates (
 			TemplateBuildState previousBuildState, bool preprocessOnly, Func<string, DateTime?> getFileWriteTime, TaskLoggingHelper logger)
diff --git a/Mono.TextTemplating.Build/TextTransform.cs b/Mono.TextTemplating.Build/TextTransform.cs
index 79a4e02..3ee1160 100644
--- a/Mono.TextTemplating.Build/TextTransform.cs
+++ b/Mono.TextTemplating.Build/TextTransform.cs
@@ -34,6 +34,7 @@ public TextTransform () : base (Messages.ResourceManager) { }
 		public bool PreprocessOnly { get; set; }
 		public bool UseLegacyPreprocessingMode { get; set; }
 		public bool TransformOutOfDateOnly { get; set; }
+		public bool UseInProcessCompiler { get; set; }
 
 		public string PreprocessTargetRuntimeIdentifier { get; set; }
 
@@ -74,7 +75,8 @@ public override bool Execute ()
 			var buildState = new TemplateBuildState {
 				IntermediateDirectory = IntermediateDirectory,
 				DefaultNamespace = DefaultNamespace,
-				PreprocessTargetRuntimeIdentifier = PreprocessTargetRuntimeIdentifier
+				PreprocessTargetRuntimeIdentifier = PreprocessTargetRuntimeIdentifier,
+				UseInProcessCompiler = UseInProcessCompiler
 			};
 
 			success &= AddParameters (buildState);
diff --git a/Mono.TextTemplating.Build/TextTransformProcessor.cs b/Mono.TextTemplating.Build/TextTransformProcessor.cs
index 3854cd2..40b93cc 100644
--- a/Mono.TextTemplating.Build/TextTransformProcessor.cs
+++ b/Mono.TextTemplating.Build/TextTransformProcessor.cs
@@ -13,6 +13,8 @@
 using Microsoft.Build.Utilities;
 using Microsoft.VisualStudio.TextTemplating;
 
+using Mono.TextTemplating;
+
 namespace Mono.TextTemplating.Build
 {
 	static class TextTransformProcessor
@@ -191,6 +193,9 @@ static void WriteOutput (MSBuildTemplateGenerator generator, string outputFile,
 		static MSBuildTemplateGenerator CreateGenerator (TemplateBuildState buildState)
 		{
 			var generator = new MSBuildTemplateGenerator ();
+			if (buildState.UseInProcessCompiler) {
+				generator.UseInProcessCompiler ();
+			}
 			if (buildState.ReferencePaths != null) {
 				generator.ReferencePaths.AddRange (buildState.ReferencePaths);
 			}