Index: lib/Support/Windows/Process.inc
===================================================================
--- lib/Support/Windows/Process.inc
+++ lib/Support/Windows/Process.inc
@@ -178,6 +178,27 @@
   return std::error_code();
 }
 
+static std::error_code
+ExpandShortFileName(const wchar_t *Arg, SmallVectorImpl<const char *> &Args,
+                    SpecificBumpPtrAllocator<char> &Allocator) {
+  SmallVector<wchar_t, MAX_PATH> LongPath;
+  DWORD Length = GetLongPathNameW(Arg, LongPath.data(), LongPath.capacity());
+  if (Length == 0) {
+    DWORD LastError = GetLastError();
+    if (LastError == ERROR_INVALID_NAME ||
+        LastError == ERROR_FILE_NOT_FOUND ||
+        LastError == ERROR_PATH_NOT_FOUND) {
+      // This argument is probably not a file name.
+      return ConvertAndPushArg(Arg, Args, Allocator);
+    }
+    return mapWindowsError(LastError);
+  } else if (Length > MAX_PATH)
+    return mapWindowsError(GetLastError());
+  LongPath.set_size(Length);
+
+  return ConvertAndPushArg(LongPath.data(), Args, Allocator);
+}
+
 /// \brief Perform wildcard expansion of Arg, or just push it into Args if it
 /// doesn't have wildcards or doesn't match any files.
 static std::error_code
@@ -185,12 +206,12 @@
                SpecificBumpPtrAllocator<char> &Allocator) {
   if (!wcspbrk(Arg, L"*?")) {
     // Arg does not contain any wildcard characters. This is the common case.
-    return ConvertAndPushArg(Arg, Args, Allocator);
+    return ExpandShortFileName(Arg, Args, Allocator);
   }
 
   if (wcscmp(Arg, L"/?") == 0 || wcscmp(Arg, L"-?") == 0) {
     // Don't wildcard expand /?. Always treat it as an option.
-    return ConvertAndPushArg(Arg, Args, Allocator);
+    return ExpandShortFileName(Arg, Args, Allocator);
   }
 
   // Extract any directory part of the argument.
@@ -201,6 +222,9 @@
   const int DirSize = Dir.size();
 
   // Search for matching files.
+  // FIXME:  This assumes the wildcard is only in the file name and not in the
+  // directory portion of the file path.  For example, it doesn't handle
+  // "*\foo.c" nor "s?c\bar.cpp".
   WIN32_FIND_DATAW FileData;
   HANDLE FindHandle = FindFirstFileW(Arg, &FileData);
   if (FindHandle == INVALID_HANDLE_VALUE) {
@@ -215,9 +239,19 @@
     if (ec)
       break;
 
-    // Push the filename onto Dir, and remove it afterwards.
+    // Append FileName to Dir, and remove it afterwards.
     llvm::sys::path::append(Dir, StringRef(FileName.data(), FileName.size()));
-    AllocateAndPush(Dir, Args, Allocator);
+    // Now we have a file spec in Dir, but it's been prematurely converted to
+    // UTF-8.  In order to expand the short file names, we need to once again
+    // convert to UTF-16.
+    SmallVector<wchar_t, MAX_PATH> WideFileSpec;
+    ec = windows::UTF8ToUTF16(llvm::StringRef(Dir.data(), Dir.size()),
+                              WideFileSpec);
+    if (ec)
+      break;
+    ec = ExpandShortFileName(WideFileSpec.data(), Args, Allocator);
+    if (ec)
+      break;
     Dir.resize(DirSize);
   } while (FindNextFileW(FindHandle, &FileData));