Index: docs/CommandGuide/clang.rst
===================================================================
--- docs/CommandGuide/clang.rst
+++ docs/CommandGuide/clang.rst
@@ -107,6 +107,11 @@
  Specify the C++ standard library to use; supported options are libstdc++ and
  libc++.
 
+.. option:: -rtlib=<library>
+
+ Specify the compiler runtime library to use; supported options are libgcc and
+ compiler-rt.
+
 .. option:: -ansi
 
  Same as -std=c89.
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1860,7 +1860,8 @@
 def resource_dir_EQ : Joined<["-"], "resource-dir=">, Flags<[DriverOption]>,
   Alias<resource_dir>;
 def rpath : Separate<["-"], "rpath">, Flags<[LinkerInput]>;
-def rtlib_EQ : Joined<["-", "--"], "rtlib=">;
+def rtlib_EQ : Joined<["-", "--"], "rtlib=">,
+  HelpText<"Compiler runtime library to use">;
 def r : Flag<["-"], "r">, Flags<[LinkerInput,NoArgumentUnused]>;
 def save_temps_EQ : Joined<["-", "--"], "save-temps=">, Flags<[DriverOption]>,
   HelpText<"Save intermediate compilation results.">;