Index: cfe/trunk/include/clang/Driver/Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/Options.td
+++ cfe/trunk/include/clang/Driver/Options.td
@@ -1335,6 +1335,10 @@
 def fno_diagnostics_show_option : Flag<["-"], "fno-diagnostics-show-option">, Group<f_Group>;
 def fno_diagnostics_show_note_include_stack : Flag<["-"], "fno-diagnostics-show-note-include-stack">,
     Flags<[CC1Option]>, Group<f_Group>;
+def fdigraphs : Flag<["-"], "fdigraphs">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Enable alternative token representations '<:', ':>', '<%', '%>', '%:', '%:%:' (default)">;
+def fno_digraphs : Flag<["-"], "fno-digraphs">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Disallow alternative token representations '<:', ':>', '<%', '%>', '%:', '%:%:'">;
 def fno_declspec : Flag<["-"], "fno-declspec">, Group<f_clang_Group>,
   HelpText<"Disallow __declspec as a keyword">, Flags<[CC1Option]>;
 def fno_dollars_in_identifiers : Flag<["-"], "fno-dollars-in-identifiers">, Group<f_Group>,
Index: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp
@@ -3925,6 +3925,7 @@
   // Forward -f (flag) options which we can pass directly.
   Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
   Args.AddLastArg(CmdArgs, options::OPT_fheinous_gnu_extensions);
+  Args.AddLastArg(CmdArgs, options::OPT_fdigraphs, options::OPT_fno_digraphs);
   Args.AddLastArg(CmdArgs, options::OPT_fno_operator_names);
   Args.AddLastArg(CmdArgs, options::OPT_femulated_tls,
                   options::OPT_fno_emulated_tls);
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -2173,6 +2173,8 @@
   Opts.GNUKeywords = Args.hasFlag(OPT_fgnu_keywords, OPT_fno_gnu_keywords,
                                   Opts.GNUKeywords);
 
+  Opts.Digraphs = Args.hasFlag(OPT_fdigraphs, OPT_fno_digraphs, Opts.Digraphs);
+
   if (Args.hasArg(OPT_fno_operator_names))
     Opts.CXXOperatorNames = 0;
 
Index: cfe/trunk/test/Lexer/digraph.c
===================================================================
--- cfe/trunk/test/Lexer/digraph.c
+++ cfe/trunk/test/Lexer/digraph.c
@@ -1,6 +1,13 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -ffreestanding %s
-// expected-no-diagnostics
+// RUN: %clang_cc1 -DDIGRAPHS=1 -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -DDIGRAPHS=1 -fno-digraphs -fdigraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -fno-digraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -fdigraphs -fno-digraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -std=c89 -DDIGRAPHS=1 -fdigraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -std=c89 -fno-digraphs -fsyntax-only -verify -ffreestanding %s
+
+#if DIGRAPHS
 
+// expected-no-diagnostics
 %:include <stdint.h>
 
     %:ifndef BUFSIZE
@@ -14,3 +21,15 @@
             d<:len:> = s<:len:>;
         %>
     %>
+#else
+
+// expected-error@+1 {{expected identifier or '('}}
+%:include <stdint.h>
+;
+// expected-error@+1 {{expected ')'}} expected-note@+1{{to match this '('}}
+void copy(char d<::>);
+
+// expected-error@+1 {{expected function body}}
+void copy() <% %>
+
+#endif