diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 62d15117c4f7fe531fa94e6e77b377f59abc128d..ec1897ca4cd7a459d103fa74d05de6bf97e9ac79 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,20 @@
+2011-07-20  Benjamin Kosnik  <bkoz@redhat.com>
+	    Daniel Krugler  <daniel.kruegler@googlemail.com>
+
+	* include/std/chrono: (system_clock::is_steady): Update to N3291
+	from is_monotonic.
+	(time_point): Add constexpr to nonmember arithmetic operators.
+	* src/chrono.cc: Modify for above.
+	* src/compatibility-c++0x.cc: Same.
+	* testsuite/20_util/time_point/nonmember/constexpr.cc: New.
+	* testsuite/20_util/time_point/1.cc: Modify.
+	* testsuite/20_util/system_clock/constexpr_data.cc: Modify.
+	* testsuite/20_util/system_clock/1.cc: Modify.
+	* testsuite/20_util/monotonic_clock/constexpr_data.cc: Move to...
+	* testsuite/20_util/steady_clock/constexpr_data.cc: ...here.
+	* testsuite/30_threads/condition_variable/members/2.cc: Modify.
+	* testsuite/30_threads/condition_variable_any/members/2.cc: Modify.
+
 2011-07-20  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* include/std/system_error: Use noexcept.
@@ -1544,7 +1561,7 @@
 2011-05-19  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* include/std/tuple (tuple<>::operator=(tuple&&)): Specify as
-        noexcept.
+	noexcept.
 	(__get_helper): Likewise.
 	(_Head_base<>::_M_head, _Tuple_impl<>::_M_head, _M_tail): Likewise.
 	* include/bits/move.h (swap): Likewise.
@@ -2237,8 +2254,8 @@
 
 2011-03-31  Jeffrey Yasskin  <jyasskin@google.com>
 
-        * libsupc++/exception_ptr.h: Forward-declare std::type_info.
-        * libsupc++/nested_exception.h (__throw_with_nested): Remove a
+	* libsupc++/exception_ptr.h: Forward-declare std::type_info.
+	* libsupc++/nested_exception.h (__throw_with_nested): Remove a
 	redundant default argument from std::__throw_with_nested.
 
 2011-03-31  Paolo Carlini  <paolo.carlini@oracle.com>
diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono
index ed8fc3033068424469bc69cf3baddbaf31f5b283..f64fd6e1e7b14bb930408eb272a94e2445c8e073 100644
--- a/libstdc++-v3/include/std/chrono
+++ b/libstdc++-v3/include/std/chrono
@@ -585,7 +585,7 @@ _GLIBCXX_END_NAMESPACE_VERSION
 
     template<typename _Clock, typename _Dur1,
 	     typename _Rep2, typename _Period2>
-      inline time_point<_Clock,
+      inline constexpr time_point<_Clock,
 	typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
       operator+(const time_point<_Clock, _Dur1>& __lhs,
 		const duration<_Rep2, _Period2>& __rhs)
@@ -593,27 +593,37 @@ _GLIBCXX_END_NAMESPACE_VERSION
 	typedef duration<_Rep2, _Period2>			__dur2;
 	typedef typename common_type<_Dur1,__dur2>::type	__ct;
 	typedef time_point<_Clock, __ct> 			__time_point;
-	return __time_point(__lhs) += __rhs;
+	return __time_point(__lhs.time_since_epoch() + __rhs);
       }
 
     template<typename _Rep1, typename _Period1,
 	     typename _Clock, typename _Dur2>
-      inline time_point<_Clock,
+      inline constexpr time_point<_Clock,
 	typename common_type<duration<_Rep1, _Period1>, _Dur2>::type>
       operator+(const duration<_Rep1, _Period1>& __lhs,
 		const time_point<_Clock, _Dur2>& __rhs)
-      { return __rhs + __lhs; }
+      { 
+	typedef duration<_Rep1, _Period1>			__dur1;
+	typedef typename common_type<__dur1,_Dur2>::type	__ct;
+	typedef time_point<_Clock, __ct> 			__time_point;
+	return __time_point(__rhs.time_since_epoch() + __lhs); 
+      }
 
     template<typename _Clock, typename _Dur1,
 	     typename _Rep2, typename _Period2>
-      inline time_point<_Clock,
+      inline constexpr time_point<_Clock,
 	typename common_type<_Dur1, duration<_Rep2, _Period2>>::type>
       operator-(const time_point<_Clock, _Dur1>& __lhs,
 		const duration<_Rep2, _Period2>& __rhs)
-      { return __lhs + (-__rhs); }
+      { 
+	typedef duration<_Rep2, _Period2>			__dur2;
+	typedef typename common_type<_Dur1,__dur2>::type	__ct;
+	typedef time_point<_Clock, __ct> 			__time_point;
+	return __time_point(__lhs.time_since_epoch() -__rhs); 
+      }
 
     template<typename _Clock, typename _Dur1, typename _Dur2>
-      inline typename common_type<_Dur1, _Dur2>::type
+      inline constexpr typename common_type<_Dur1, _Dur2>::type
       operator-(const time_point<_Clock, _Dur1>& __lhs,
 		const time_point<_Clock, _Dur2>& __rhs)
       { return __lhs.time_since_epoch() - __rhs.time_since_epoch(); }
@@ -673,7 +683,7 @@ _GLIBCXX_END_NAMESPACE_VERSION
 		    < system_clock::duration::zero(),
 		    "a clock's minimum duration cannot be less than its epoch");
 
-      static constexpr bool is_monotonic = false;
+      static constexpr bool is_steady = false;
 
       static time_point
       now() throw ();
@@ -696,21 +706,21 @@ _GLIBCXX_END_NAMESPACE_VERSION
     };
 
 #ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
-    /// monotonic_clock
-    struct monotonic_clock
+    /// steady_clock
+    struct steady_clock
     {
       typedef chrono::nanoseconds 				duration;
       typedef duration::rep	  				rep;
       typedef duration::period	  				period;
-      typedef chrono::time_point<monotonic_clock, duration> 	time_point;
+      typedef chrono::time_point<steady_clock, duration> 	time_point;
 
-      static constexpr bool is_monotonic = true;
+      static constexpr bool is_steady = true;
 
       static time_point
       now();
     };
 #else
-    typedef system_clock monotonic_clock;
+    typedef system_clock steady_clock;
 #endif
 
     typedef system_clock high_resolution_clock;
diff --git a/libstdc++-v3/src/chrono.cc b/libstdc++-v3/src/chrono.cc
index 6b5e669a7dca0b1764e5df5bf96b092b0cc7d03c..07c932a1ad8a13cf46e27cf4c9792be6431729ca 100644
--- a/libstdc++-v3/src/chrono.cc
+++ b/libstdc++-v3/src/chrono.cc
@@ -39,7 +39,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
   {
   _GLIBCXX_BEGIN_NAMESPACE_VERSION
  
-   constexpr bool system_clock::is_monotonic;
+    constexpr bool system_clock::is_steady;
 
     system_clock::time_point
     system_clock::now() throw ()
@@ -63,10 +63,10 @@ namespace std _GLIBCXX_VISIBILITY(default)
     }
     
 #ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
-    constexpr bool monotonic_clock::is_monotonic;
+    constexpr bool steady_clock::is_steady;
     
-    monotonic_clock::time_point
-    monotonic_clock::now()
+    steady_clock::time_point
+    steady_clock::now()
     {
       timespec tp;
       // -EINVAL, -EFAULT
diff --git a/libstdc++-v3/src/compatibility-c++0x.cc b/libstdc++-v3/src/compatibility-c++0x.cc
index 08a572761f9c2b73fd10db085e6511119201414a..c5e1db092a57858a54b68c06a7d1736532c1bd8e 100644
--- a/libstdc++-v3/src/compatibility-c++0x.cc
+++ b/libstdc++-v3/src/compatibility-c++0x.cc
@@ -1,6 +1,6 @@
 // Compatibility symbols for previous versions, C++0x bits -*- C++ -*-
 
-// Copyright (C) 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2009, 2010, 2011 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -81,4 +81,17 @@ namespace std _GLIBCXX_VISIBILITY(default)
       const size_t __tmp = std::_Hash_impl::hash(__e._M_value);
       return std::_Hash_impl::__hash_combine(__e._M_cat, __tmp);
     }
+
+
+  // gcc-4.7.0
+  // <chrono> changes is_monotonic to is_steady.
+  namespace chrono
+  {
+    struct system_clock
+    {
+      static constexpr bool is_monotonic = false;
+    };
+    constexpr bool system_clock::is_monotonic;
+  } // namespace chrono
 }
+
diff --git a/libstdc++-v3/testsuite/20_util/monotonic_clock/constexpr_data.cc b/libstdc++-v3/testsuite/20_util/steady_clock/constexpr_data.cc
similarity index 93%
rename from libstdc++-v3/testsuite/20_util/monotonic_clock/constexpr_data.cc
rename to libstdc++-v3/testsuite/20_util/steady_clock/constexpr_data.cc
index 34477ea183880ecd940ba9c46ae97559c7b3964f..2b497cfa35bf6e7da7c0dc1f84ee537160355327 100644
--- a/libstdc++-v3/testsuite/20_util/monotonic_clock/constexpr_data.cc
+++ b/libstdc++-v3/testsuite/20_util/steady_clock/constexpr_data.cc
@@ -34,7 +34,7 @@ namespace __gnu_test
 	  void __constraint()
 	  {
 	    constexpr auto v1 __attribute__((unused))
-	      = _Ttesttype::is_monotonic;
+	      = _Ttesttype::is_steady;
 	  }
 	};
 
@@ -47,6 +47,6 @@ namespace __gnu_test
 int main()
 {
   __gnu_test::constexpr_member_data test;
-  test.operator()<std::chrono::monotonic_clock>();
+  test.operator()<std::chrono::steady_clock>();
   return 0;
 }
diff --git a/libstdc++-v3/testsuite/20_util/system_clock/1.cc b/libstdc++-v3/testsuite/20_util/system_clock/1.cc
index ead20873c7bab43aba9b12ef3a0a488ae82afedc..77426e90ce16ae155de8da6e74aa68da9b3bf764 100644
--- a/libstdc++-v3/testsuite/20_util/system_clock/1.cc
+++ b/libstdc++-v3/testsuite/20_util/system_clock/1.cc
@@ -1,7 +1,7 @@
 // { dg-options "-std=gnu++0x" }
 // { dg-require-cstdint "" }
 
-// Copyright (C) 2008, 2009, 2010 Free Software Foundation
+// Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -29,8 +29,8 @@ main()
   using namespace std::chrono;
 
   system_clock::time_point t1 = system_clock::now();
-  bool is_monotonic = system_clock::is_monotonic;
-  is_monotonic = is_monotonic; // suppress unused warning
+  bool is_steady = system_clock::is_steady;
+  is_steady = is_steady; // suppress unused warning
   std::time_t t2 = system_clock::to_time_t(t1);
   system_clock::time_point t3 = system_clock::from_time_t(t2);
   t3 = t3; // suppress unused warning
diff --git a/libstdc++-v3/testsuite/20_util/system_clock/constexpr_data.cc b/libstdc++-v3/testsuite/20_util/system_clock/constexpr_data.cc
index 2407ef16a711d62963a641b890901988fa5b669f..8312f53659290162494f60622f8e207240ff0727 100644
--- a/libstdc++-v3/testsuite/20_util/system_clock/constexpr_data.cc
+++ b/libstdc++-v3/testsuite/20_util/system_clock/constexpr_data.cc
@@ -1,7 +1,7 @@
 // { dg-do compile }
 // { dg-options "-std=gnu++0x" }
 
-// Copyright (C) 2010 Free Software Foundation, Inc.
+// Copyright (C) 2010, 2011 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -34,7 +34,7 @@ namespace __gnu_test
 	  void __constraint()
 	  {
 	    constexpr auto v1 __attribute__((unused))
-	      = _Ttesttype::is_monotonic;
+	      = _Ttesttype::is_steady;
 	  }
 	};
 
diff --git a/libstdc++-v3/testsuite/20_util/time_point/1.cc b/libstdc++-v3/testsuite/20_util/time_point/1.cc
index e18c6e58cf0377884bc17c5b21ac2c9264b6a70b..11a6ac49525a57a350c429cb22ef7c8365e1ce47 100644
--- a/libstdc++-v3/testsuite/20_util/time_point/1.cc
+++ b/libstdc++-v3/testsuite/20_util/time_point/1.cc
@@ -1,7 +1,7 @@
 // { dg-options "-std=gnu++0x" }
 // { dg-require-cstdint "" }
 
-// Copyright (C) 2008, 2009 Free Software Foundation
+// Copyright (C) 2008, 2009, 2011 Free Software Foundation
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -33,8 +33,8 @@ test01()
   time_point<system_clock> t1;
   VERIFY(t1.time_since_epoch() == system_clock::duration::zero());
 
-  time_point<monotonic_clock> t2;
-  VERIFY(t2.time_since_epoch() == monotonic_clock::duration::zero());
+  time_point<steady_clock> t2;
+  VERIFY(t2.time_since_epoch() == steady_clock::duration::zero());
 
   time_point<high_resolution_clock> t3;
   VERIFY(t3.time_since_epoch() == high_resolution_clock::duration::zero());
diff --git a/libstdc++-v3/testsuite/20_util/time_point/nonmember/constexpr.cc b/libstdc++-v3/testsuite/20_util/time_point/nonmember/constexpr.cc
new file mode 100644
index 0000000000000000000000000000000000000000..37b39f431336eb10f492ae95a78235be40615a0f
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/time_point/nonmember/constexpr.cc
@@ -0,0 +1,45 @@
+// { dg-do compile }
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2011 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <chrono>
+#include <testsuite_hooks.h>
+
+int main()
+{
+  bool test __attribute__((unused)) = true;
+  using namespace std::chrono;
+  
+  typedef time_point<system_clock> time_type;
+
+  constexpr time_type t1(seconds(1));
+  constexpr time_type t2(seconds(30));
+  constexpr time_type t3(seconds(60));
+  
+  constexpr duration<int> d0(12);
+  constexpr duration<int> d1(3);
+
+  constexpr auto r1 = t1 + d0;
+  constexpr auto r2 = d1 + t2;
+
+  constexpr auto r3 = t1 - d0;
+  constexpr auto r4 = t2 - t3;
+
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/30_threads/condition_variable/members/2.cc b/libstdc++-v3/testsuite/30_threads/condition_variable/members/2.cc
index f4904ada547606d122b04dd28c6116c79afa0b9c..0938bc463280c66f32cb5ffb77d7386a356ee3b9 100644
--- a/libstdc++-v3/testsuite/30_threads/condition_variable/members/2.cc
+++ b/libstdc++-v3/testsuite/30_threads/condition_variable/members/2.cc
@@ -5,7 +5,7 @@
 // { dg-require-cstdint "" }
 // { dg-require-gthreads "" }
 
-// Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -38,10 +38,10 @@ void test01()
       std::mutex m;
       std::unique_lock<std::mutex> l(m);
 
-      auto then = std::chrono::monotonic_clock::now();
+      auto then = std::chrono::steady_clock::now();
       std::cv_status result = c1.wait_until(l, then + ms);
       VERIFY( result == std::cv_status::timeout );
-      VERIFY( (std::chrono::monotonic_clock::now() - then) >= ms );
+      VERIFY( (std::chrono::steady_clock::now() - then) >= ms );
       VERIFY( l.owns_lock() );
     }
   catch (const std::system_error& e)
diff --git a/libstdc++-v3/testsuite/30_threads/condition_variable_any/members/2.cc b/libstdc++-v3/testsuite/30_threads/condition_variable_any/members/2.cc
index 8e58dce818b975e53859560a003560048a81a2b8..3ad13a379285f594f324ad83947492ca82804e38 100644
--- a/libstdc++-v3/testsuite/30_threads/condition_variable_any/members/2.cc
+++ b/libstdc++-v3/testsuite/30_threads/condition_variable_any/members/2.cc
@@ -5,7 +5,7 @@
 // { dg-require-cstdint "" }
 // { dg-require-gthreads "" }
 
-// Copyright (C) 2010 Free Software Foundation, Inc.
+// Copyright (C) 2010, 2011 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -63,10 +63,10 @@ void test01()
       Mutex m;
       m.lock();
 
-      auto then = std::chrono::monotonic_clock::now();
+      auto then = std::chrono::steady_clock::now();
       std::cv_status result = c1.wait_until(m, then + ms);
       VERIFY( result == std::cv_status::timeout );
-      VERIFY( (std::chrono::monotonic_clock::now() - then) >= ms );
+      VERIFY( (std::chrono::steady_clock::now() - then) >= ms );
       VERIFY( m.locked );
     }
   catch (const std::system_error& e)