Index: include/clang/Basic/Cuda.h
===================================================================
--- include/clang/Basic/Cuda.h
+++ include/clang/Basic/Cuda.h
@@ -46,6 +46,7 @@
   SM_62,
   SM_70,
   SM_72,
+  LAST,
 };
 const char *CudaArchToString(CudaArch A);
 
Index: lib/Basic/Cuda.cpp
===================================================================
--- lib/Basic/Cuda.cpp
+++ lib/Basic/Cuda.cpp
@@ -26,6 +26,8 @@
 
 const char *CudaArchToString(CudaArch A) {
   switch (A) {
+  case CudaArch::LAST:
+    break;
   case CudaArch::UNKNOWN:
     return "unknown";
   case CudaArch::SM_20:
@@ -133,6 +135,8 @@
 
 CudaVirtualArch VirtualArchForCudaArch(CudaArch A) {
   switch (A) {
+  case CudaArch::LAST:
+    break;
   case CudaArch::UNKNOWN:
     return CudaVirtualArch::UNKNOWN;
   case CudaArch::SM_20:
@@ -168,6 +172,8 @@
 
 CudaVersion MinVersionForCudaArch(CudaArch A) {
   switch (A) {
+  case CudaArch::LAST:
+    break;
   case CudaArch::UNKNOWN:
     return CudaVersion::UNKNOWN;
   case CudaArch::SM_20:
Index: lib/Basic/Targets/NVPTX.h
===================================================================
--- lib/Basic/Targets/NVPTX.h
+++ lib/Basic/Targets/NVPTX.h
@@ -98,6 +98,12 @@
     return StringToCudaArch(Name) != CudaArch::UNKNOWN;
   }
 
+  void fillValidCPUList(SmallVectorImpl<StringRef> &Values) const override {
+    for (int i = static_cast<int>(CudaArch::SM_20);
+         i < static_cast<int>(CudaArch::LAST); ++i)
+      Values.emplace_back(CudaArchToString(static_cast<CudaArch>(i)));
+  }
+
   bool setCPU(const std::string &Name) override {
     GPU = StringToCudaArch(Name);
     return GPU != CudaArch::UNKNOWN;
Index: lib/Basic/Targets/NVPTX.cpp
===================================================================
--- lib/Basic/Targets/NVPTX.cpp
+++ lib/Basic/Targets/NVPTX.cpp
@@ -157,6 +157,8 @@
     // Set __CUDA_ARCH__ for the GPU specified.
     std::string CUDAArchCode = [this] {
       switch (GPU) {
+      case CudaArch::LAST:
+        break;
       case CudaArch::UNKNOWN:
         assert(false && "No GPU arch when compiling CUDA device code.");
         return "";
Index: test/Misc/target-invalid-cpu-note.c
===================================================================
--- test/Misc/target-invalid-cpu-note.c
+++ test/Misc/target-invalid-cpu-note.c
@@ -31,3 +31,8 @@
 // X86_64-SAME: icelake, knl, knm, k8, athlon64, athlon-fx, opteron, k8-sse3,
 // X86_64-SAME: athlon64-sse3, opteron-sse3, amdfam10, barcelona, btver1,
 // X86_64-SAME: btver2, bdver1, bdver2, bdver3, bdver4, znver1, x86-64
+
+// RUN: not %clang_cc1 -triple nvptx--- -target-cpu not-a-cpu -fsyntax-only %s 2>&1 | FileCheck %s --check-prefix NVPTX
+// NVPTX: error: unknown target CPU 'not-a-cpu'
+// NVPTX: note: valid target CPU values are: sm_20, sm_21, sm_30, sm_32, sm_35,
+// NVPTX-SAME: sm_37, sm_50, sm_52, sm_53, sm_60, sm_61, sm_62, sm_70, sm_72