diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 4b9b197a0da..91706ad8a6c 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2011-02-28  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* testsuite/20_util/ratio/comparisons/comp3.cc: New.
+
+2011-02-28  Marc Glisse  <marc.glisse@normalesup.org>
+
+	PR libstdc++/42622
+	* include/std/ratio (ratio_less): Reimplement to never overflow.
+	* testsuite/20_util/ratio/comparisons/comp2.cc: Extend.
+
 2011-02-24  Benjamin Kosnik  <bkoz@redhat.com>
 
 	* testsuite/18_support/type_info/fundamental.cc: New.
diff --git a/libstdc++-v3/include/std/ratio b/libstdc++-v3/include/std/ratio
index 69c0b6e14bb..2b10da7c688 100644
--- a/libstdc++-v3/include/std/ratio
+++ b/libstdc++-v3/include/std/ratio
@@ -1,6 +1,6 @@
 // ratio -*- C++ -*-
 
-// 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 
@@ -274,9 +274,42 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : integral_constant<bool, !ratio_equal<_R1, _R2>::value>
     { };
 
-  template<typename _R1>
+  // 0 <= _Ri < 1
+  template<typename _R1, typename _R2>
+    struct __ratio_less_impl_2;
+
+  // _Ri > 0
+  template<typename _R1, typename _R2, intmax_t __q1 = _R1::num / _R1::den,
+           intmax_t __q2 = _R2::num / _R2::den, bool __eq = (__q1 == __q2)>
     struct __ratio_less_impl_1
-    : integral_constant<bool, _R1::num < _R1::den>
+    : __ratio_less_impl_2<ratio<_R1::num % _R1::den, _R1::den>,
+           ratio<_R2::num % _R2::den, _R2::den> >::type
+    { }; 
+
+  template<typename _R1, typename _R2, intmax_t __q1, intmax_t __q2>
+    struct __ratio_less_impl_1<_R1, _R2, __q1, __q2, false>
+    : integral_constant<bool, (__q1 < __q2) >
+    { };
+
+  template<typename _R1, typename _R2>
+    struct __ratio_less_impl_2
+    : __ratio_less_impl_1<ratio<_R2::den, _R2::num>,
+           ratio<_R1::den, _R1::num> >::type
+    { }; 
+
+  template<intmax_t __d1, typename _R2>
+    struct __ratio_less_impl_2<ratio<0, __d1>, _R2>
+    : integral_constant<bool, true>
+    { }; 
+
+  template<typename _R1, intmax_t __d2>
+    struct __ratio_less_impl_2<_R1, ratio<0, __d2> >
+    : integral_constant<bool, false>
+    { }; 
+
+  template<intmax_t __d1, intmax_t __d2>
+    struct __ratio_less_impl_2<ratio<0, __d1>, ratio<0, __d2> >
+    : integral_constant<bool, false>
     { }; 
 
   template<typename _R1, typename _R2,
@@ -286,7 +319,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	   bool = (__static_sign<_R1::num>::value == -1
 		   && __static_sign<_R2::num>::value == -1)>
     struct __ratio_less_impl
-    : __ratio_less_impl_1<typename ratio_divide<_R1, _R2>::type>::type
+    : __ratio_less_impl_1<_R1, _R2>::type
     { };
 
   template<typename _R1, typename _R2>
@@ -296,7 +329,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   template<typename _R1, typename _R2>
     struct __ratio_less_impl<_R1, _R2, false, true>
-    : __ratio_less_impl_1<typename ratio_divide<_R2, _R1>::type>::type
+    : __ratio_less_impl_1<ratio<-_R2::num, _R2::den>,
+           ratio<-_R1::num, _R1::den> >::type
     { };
 
   /// ratio_less
diff --git a/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp2.cc b/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp2.cc
index 151dc64450e..20da30cbe25 100644
--- a/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp2.cc
+++ b/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp2.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
@@ -48,6 +48,9 @@ test01()
 
   VERIFY( (std::ratio_less<std::ratio<-M, M - 1>,
            std::ratio<-M, M - 2>>::value == 0) );
+
+  VERIFY( (std::ratio_less<std::ratio<M - 2, M - 1>,
+           std::ratio<M - 1, M>>::value == 1) );
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp3.cc b/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp3.cc
new file mode 100644
index 00000000000..f8c0c486b4a
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/ratio/comparisons/comp3.cc
@@ -0,0 +1,75 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-require-cstdint "" }
+
+// 2011-02-28  Paolo Carlini  <paolo.carlini@oracle.com>
+
+// Copyright (C) 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
+// 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 <ratio>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  VERIFY( (std::ratio_less<std::ratio<59, 29131>,
+	                   std::ratio<59, 29129>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<4733, 13>,
+	                   std::ratio<4751, 13>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<25703, 25717>,
+	                   std::ratio<25733, 25741>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<631, 769>,
+	                   std::ratio<673, 773>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<8353, 16903>,
+	                   std::ratio<17891, 32099>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<2311, 18701>,
+	                   std::ratio<18457, 19571>>::value == 1) );
+
+  VERIFY( (std::ratio_less<std::ratio<60, 29132>,
+	                   std::ratio<60, 29130>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<4734, 14>,
+	                   std::ratio<4752, 14>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<25704, 25718>,
+	                   std::ratio<25732, 25742>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<632, 770>,
+	                   std::ratio<674, 774>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<8352, 16904>,
+	                   std::ratio<17892, 32100>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<2312, 18702>,
+	                   std::ratio<18458, 19572>>::value == 1) );
+
+  VERIFY( (std::ratio_less<std::ratio<58, 29130>,
+	                   std::ratio<58, 29128>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<4732, 12>,
+	                   std::ratio<4750, 12>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<25702, 25716>,
+	                   std::ratio<25734, 25740>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<630, 768>,
+	                   std::ratio<672, 772>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<8354, 16902>,
+	                   std::ratio<17890, 32102>>::value == 1) );
+  VERIFY( (std::ratio_less<std::ratio<2310, 18700>,
+	                   std::ratio<18456, 19570>>::value == 1) );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}