Index: cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
@@ -23,6 +23,9 @@
 def err_drv_invalid_arch_name : Error<
   "invalid arch name '%0'">;
 def err_drv_cuda_bad_gpu_arch : Error<"Unsupported CUDA gpu architecture: %0">;
+def err_drv_no_cuda_installation : Error<
+  "cannot find CUDA installation.  Provide its path via --cuda-path, or pass "
+  "-nocudainc to build without CUDA includes.">;
 def err_drv_invalid_thread_model_for_target : Error<
   "invalid thread model '%0' in '%1' for this target">;
 def err_drv_invalid_linker_name : Error<
Index: cfe/trunk/lib/Driver/ToolChains.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains.cpp
+++ cfe/trunk/lib/Driver/ToolChains.cpp
@@ -4118,11 +4118,14 @@
   if (DriverArgs.hasArg(options::OPT_nocudainc))
     return;
 
-  if (CudaInstallation.isValid()) {
-    addSystemInclude(DriverArgs, CC1Args, CudaInstallation.getIncludePath());
-    CC1Args.push_back("-include");
-    CC1Args.push_back("__clang_cuda_runtime_wrapper.h");
+  if (!CudaInstallation.isValid()) {
+    getDriver().Diag(diag::err_drv_no_cuda_installation);
+    return;
   }
+
+  addSystemInclude(DriverArgs, CC1Args, CudaInstallation.getIncludePath());
+  CC1Args.push_back("-include");
+  CC1Args.push_back("__clang_cuda_runtime_wrapper.h");
 }
 
 bool Linux::isPIEDefault() const { return getSanitizerArgs().requiresPIE(); }