Index: include/clang/Driver/Driver.h
===================================================================
--- include/clang/Driver/Driver.h
+++ include/clang/Driver/Driver.h
@@ -316,7 +316,8 @@
   /// PrintHelp - Print the help text.
   ///
   /// \param ShowHidden - Show hidden options.
-  void PrintHelp(bool ShowHidden) const;
+  /// \param ShowHidden - Show hidden options without help string, too.
+  void PrintHelp(bool ShowHidden, bool ShowUndocumented) const;
 
   /// PrintVersion - Print the driver version.
   void PrintVersion(const Compilation &C, raw_ostream &OS) const;
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1590,6 +1590,7 @@
 def _force_link_EQ : Joined<["--"], "force-link=">, Alias<u>;
 def _force_link : Separate<["--"], "force-link">, Alias<u>;
 def _help_hidden : Flag<["--"], "help-hidden">;
+def _help_hidden_all : Flag<["--"], "help-hidden-all">;
 def _imacros_EQ : Joined<["--"], "imacros=">, Alias<imacros>;
 def _include_barrier : Flag<["--"], "include-barrier">, Alias<I_>;
 def _include_directory_after_EQ : Joined<["--"], "include-directory-after=">, Alias<idirafter>;
Index: lib/Driver/Driver.cpp
===================================================================
--- lib/Driver/Driver.cpp
+++ lib/Driver/Driver.cpp
@@ -643,7 +643,7 @@
   return 0;
 }
 
-void Driver::PrintHelp(bool ShowHidden) const {
+void Driver::PrintHelp(bool ShowHidden, bool ShowUndocumented) const {
   unsigned IncludedFlagsBitmask;
   unsigned ExcludedFlagsBitmask;
   std::tie(IncludedFlagsBitmask, ExcludedFlagsBitmask) =
@@ -654,7 +654,8 @@
     ExcludedFlagsBitmask |= HelpHidden;
 
   getOpts().PrintHelp(llvm::outs(), Name.c_str(), DriverTitle.c_str(),
-                      IncludedFlagsBitmask, ExcludedFlagsBitmask);
+                      IncludedFlagsBitmask, ExcludedFlagsBitmask,
+                      ShowUndocumented);
 }
 
 void Driver::PrintVersion(const Compilation &C, raw_ostream &OS) const {
@@ -709,8 +710,11 @@
   }
 
   if (C.getArgs().hasArg(options::OPT_help) ||
-      C.getArgs().hasArg(options::OPT__help_hidden)) {
-    PrintHelp(C.getArgs().hasArg(options::OPT__help_hidden));
+      C.getArgs().hasArg(options::OPT__help_hidden) ||
+      C.getArgs().hasArg(options::OPT__help_hidden_all)) {
+    PrintHelp(C.getArgs().hasArg(options::OPT__help_hidden) ||
+                  C.getArgs().hasArg(options::OPT__help_hidden_all),
+              C.getArgs().hasArg(options::OPT__help_hidden_all));
     return false;
   }