diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -17,6 +17,7 @@
 #include "clang/Basic/TargetOptions.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/FormatVariadic.h"
 
 using namespace clang;
 using namespace CodeGen;
@@ -94,4 +95,11 @@
     F->addFnAttr(ShaderAttrKindStr,
                  ShaderAttr->ConvertShaderTypeToStr(ShaderAttr->getType()));
   }
+  if (HLSLNumThreadsAttr *NumThreadsAttr = FD->getAttr<HLSLNumThreadsAttr>()) {
+    const StringRef NumThreadsKindStr = "hlsl.numthreads";
+    StringRef NumThreadsStr =
+        formatv("{0},{1},{2}", NumThreadsAttr->getX(), NumThreadsAttr->getY(),
+                NumThreadsAttr->getZ());
+    F->addFnAttr(NumThreadsKindStr, NumThreadsStr);
+  }
 }
diff --git a/clang/test/CodeGenHLSL/entry.hlsl b/clang/test/CodeGenHLSL/entry.hlsl
--- a/clang/test/CodeGenHLSL/entry.hlsl
+++ b/clang/test/CodeGenHLSL/entry.hlsl
@@ -3,8 +3,9 @@
 // Make sure not mangle entry.
 // CHECK:define void @foo()
 // Make sure add function attribute.
-// CHECK:"dx.shader"="compute"
-[numthreads(1,1,1)]
+// CHECK:"hlsl.numthreads"="16,8,1"
+// CHECK-SAME:"dx.shader"="compute"
+[numthreads(16,8,1)]
 void foo() {
 
 }