Index: c-family/c-cppbuiltin.c
===================================================================
--- c-family/c-cppbuiltin.c	(revision 198231)
+++ c-family/c-cppbuiltin.c	(working copy)
@@ -713,8 +713,10 @@ c_cpp_builtins (cpp_reader *pfile)
 	cpp_define (pfile, "__DEPRECATED");
       if (flag_rtti)
 	cpp_define (pfile, "__GXX_RTTI");
-      if (cxx_dialect >= cxx0x)
+      if (cxx_dialect == cxx0x)
         cpp_define (pfile, "__GXX_EXPERIMENTAL_CXX0X__");
+      if (cxx_dialect >= cxx1y)
+        cpp_define (pfile, "__GXX_EXPERIMENTAL_CXX1Y__");
     }
   /* Note that we define this for C as well, so that we know if
      __attribute__((cleanup)) will interface with EH.  */
Index: doc/cpp.texi
===================================================================
--- doc/cpp.texi	(revision 198231)
+++ doc/cpp.texi	(working copy)
@@ -2319,6 +2319,13 @@ features likely to be included in C++0x are availa
 features are experimental, and may change or be removed in future
 versions of GCC.
 
+@item __GXX_EXPERIMENTAL_CXX1Y__
+This macro is defined when compiling a C++ source file with the option
+@option{-std=c++1y} or @option{-std=gnu++1y}. It indicates that some
+features likely to be included in C++1y are available. Note that these
+features are experimental, and may change or be removed in future
+versions of GCC.
+
 @item __GXX_WEAK__
 This macro is defined when compiling a C++ source file.  It has the
 value 1 if the compiler will use weak symbols, COMDAT sections, or
Index: testsuite/g++.dg/cpp1y/cxx1y_macro.C
===================================================================
--- testsuite/g++.dg/cpp1y/cxx1y_macro.C	(revision 0)
+++ testsuite/g++.dg/cpp1y/cxx1y_macro.C	(working copy)
@@ -0,0 +1,5 @@
+// { dg-options "-std=c++1y" }
+
+#ifndef __GXX_EXPERIMENTAL_CXX1Y__
+#error
+#endif