Index: llvm/tools/clang/lib/Driver/Driver.cpp
===================================================================
--- llvm.orig/tools/clang/lib/Driver/Driver.cpp
+++ llvm/tools/clang/lib/Driver/Driver.cpp
@@ -66,11 +66,11 @@ Driver::Driver(StringRef ClangExecutable
 
   // Compute the path to the resource directory.
   StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
-  SmallString<128> P(Dir);
+  SmallString<128> P((Dir != "") ? Dir : "/usr/bin/");
   if (ClangResourceDir != "")
     llvm::sys::path::append(P, ClangResourceDir);
   else
-    llvm::sys::path::append(P, "..", "lib", "clang", CLANG_VERSION_STRING);
+    llvm::sys::path::append(P, "..", "LLVM_LIBDIR", "clang", CLANG_VERSION_STRING);
   ResourceDir = P.str();
 }