Index: lib/Support/Windows/Path.inc
===================================================================
--- lib/Support/Windows/Path.inc
+++ lib/Support/Windows/Path.inc
@@ -17,6 +17,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/WindowsError.h"
 #include <fcntl.h>
 #include <io.h>
@@ -280,12 +281,26 @@
 }
 
 std::error_code access(const Twine &Path, AccessMode Mode) {
-  SmallVector<wchar_t, 128> PathUtf16;
+  SmallVector<StringRef, 12> PathExts;
+  PathExts.push_back("");
+  PathExts.push_back(".exe"); // FIXME: This must be in %PATHEXT%.
+  if (const char *PathExtEnv = std::getenv("PATHEXT"))
+    SplitString(PathExtEnv, PathExts, ";");
 
-  if (std::error_code EC = widenPath(Path, PathUtf16))
-    return EC;
+  DWORD Attributes = INVALID_FILE_ATTRIBUTES;
+
+  for (StringRef Ext : PathExts) {
+    SmallVector<wchar_t, 128> PathUtf16;
+
+    if (std::error_code EC = widenPath(Path + Ext, PathUtf16))
+      return EC;
 
-  DWORD Attributes = ::GetFileAttributesW(PathUtf16.begin());
+    Attributes = ::GetFileAttributesW(PathUtf16.begin());
+
+    if (Attributes != INVALID_FILE_ATTRIBUTES)
+      // the file exists
+      break;
+  }
 
   if (Attributes == INVALID_FILE_ATTRIBUTES) {
     // See if the file didn't actually exist.