diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index b25378eaace..322f1e42611 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -4875,12 +4875,16 @@ dnl
 AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_DUAL_ABI], [
   GLIBCXX_ENABLE(libstdcxx-dual-abi,$1,,[support two versions of std::string])
   if test x$enable_symvers = xgnu-versioned-namespace; then
-    # gnu-versioned-namespace is incompatible with the dual ABI.
-    enable_libstdcxx_dual_abi="no"
-  fi
-  if test x"$enable_libstdcxx_dual_abi" != xyes; then
+    # gnu-versioned-namespace is incompatible with the dual ABI...
     AC_MSG_NOTICE([dual ABI is disabled])
-    default_libstdcxx_abi="gcc4-compatible"
+    enable_libstdcxx_dual_abi="no"
+    # ... and use the cxx11 one.
+    default_libstdcxx_abi="new"
+  else
+    if test x"$enable_libstdcxx_dual_abi" != xyes; then
+      AC_MSG_NOTICE([dual ABI is disabled])
+      default_libstdcxx_abi="gcc4-compatible"
+    fi
   fi
   GLIBCXX_CONDITIONAL(ENABLE_DUAL_ABI, test $enable_libstdcxx_dual_abi = yes)
 ])
diff --git a/libstdc++-v3/config/locale/dragonfly/monetary_members.cc b/libstdc++-v3/config/locale/dragonfly/monetary_members.cc
index f534bbe4aeb..3f96f2b9f11 100644
--- a/libstdc++-v3/config/locale/dragonfly/monetary_members.cc
+++ b/libstdc++-v3/config/locale/dragonfly/monetary_members.cc
@@ -39,7 +39,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 // This file might be compiled twice, but we only want to define the members
 // of money_base once.
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 
   // Construct and return valid pattern consisting of some combination of:
   // space none symbol sign value
@@ -207,7 +207,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
     return __ret;
   }
-#endif
+#endif // ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 
   template<>
     void
diff --git a/libstdc++-v3/config/locale/generic/monetary_members.cc b/libstdc++-v3/config/locale/generic/monetary_members.cc
index 2c1cfeff094..a1ae136be04 100644
--- a/libstdc++-v3/config/locale/generic/monetary_members.cc
+++ b/libstdc++-v3/config/locale/generic/monetary_members.cc
@@ -36,7 +36,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 // This file might be compiled twice, but we only want to define the members
 // of money_base once.
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 
   // Construct and return valid pattern consisting of some combination of:
   // space none symbol sign value
diff --git a/libstdc++-v3/config/locale/gnu/monetary_members.cc b/libstdc++-v3/config/locale/gnu/monetary_members.cc
index 1f46ea2f53f..87561bcc821 100644
--- a/libstdc++-v3/config/locale/gnu/monetary_members.cc
+++ b/libstdc++-v3/config/locale/gnu/monetary_members.cc
@@ -37,7 +37,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 // This file might be compiled twice, but we only want to define the members
 // of money_base once.
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 
   // Construct and return valid pattern consisting of some combination of:
   // space none symbol sign value
@@ -205,7 +205,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
     return __ret;
   }
-#endif
+#endif // ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 
   extern char __narrow_multibyte_chars(const char* s, __locale_t cloc);
 
diff --git a/libstdc++-v3/config/locale/gnu/numeric_members.cc b/libstdc++-v3/config/locale/gnu/numeric_members.cc
index 220a0f8c510..cb8095e6ac7 100644
--- a/libstdc++-v3/config/locale/gnu/numeric_members.cc
+++ b/libstdc++-v3/config/locale/gnu/numeric_members.cc
@@ -39,7 +39,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   extern char __narrow_multibyte_chars(const char* s, __locale_t cloc);
 
 // This file might be compiled twice, but we only want to define this once.
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   char
   __narrow_multibyte_chars(const char* s, __locale_t cloc)
   {
@@ -84,7 +84,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
     return '\0';
   }
-#endif
+#endif // ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 
   template<>
     void
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index c4da56c3042..fd431f28547 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -70702,13 +70702,18 @@ fi
 
 
   if test x$enable_symvers = xgnu-versioned-namespace; then
-    # gnu-versioned-namespace is incompatible with the dual ABI.
-    enable_libstdcxx_dual_abi="no"
-  fi
-  if test x"$enable_libstdcxx_dual_abi" != xyes; then
+    # gnu-versioned-namespace is incompatible with the dual ABI...
     { $as_echo "$as_me:${as_lineno-$LINENO}: dual ABI is disabled" >&5
 $as_echo "$as_me: dual ABI is disabled" >&6;}
-    default_libstdcxx_abi="gcc4-compatible"
+    enable_libstdcxx_dual_abi="no"
+    # ... and use the cxx11 one.
+    default_libstdcxx_abi="new"
+  else
+    if test x"$enable_libstdcxx_dual_abi" != xyes; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: dual ABI is disabled" >&5
+$as_echo "$as_me: dual ABI is disabled" >&6;}
+      default_libstdcxx_abi="gcc4-compatible"
+    fi
   fi
 
 
diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config
index dd47f274d5f..b90efc81d33 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -337,26 +337,6 @@ namespace std
 #define _GLIBCXX_USE_CXX11_ABI
 #endif
 
-#if _GLIBCXX_USE_CXX11_ABI
-namespace std
-{
-  inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
-}
-namespace __gnu_cxx
-{
-  inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
-}
-# define _GLIBCXX_NAMESPACE_CXX11 __cxx11::
-# define _GLIBCXX_BEGIN_NAMESPACE_CXX11 namespace __cxx11 {
-# define _GLIBCXX_END_NAMESPACE_CXX11 }
-# define _GLIBCXX_DEFAULT_ABI_TAG _GLIBCXX_ABI_TAG_CXX11
-#else
-# define _GLIBCXX_NAMESPACE_CXX11
-# define _GLIBCXX_BEGIN_NAMESPACE_CXX11
-# define _GLIBCXX_END_NAMESPACE_CXX11
-# define _GLIBCXX_DEFAULT_ABI_TAG
-#endif
-
 // Non-zero if inline namespaces are used for versioning the entire library.
 #define _GLIBCXX_INLINE_VERSION 
 
@@ -415,7 +395,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Non-inline namespace for components replaced by alternates in active mode.
   namespace __cxx1998
   {
-# if _GLIBCXX_USE_CXX11_ABI
+# if _GLIBCXX_USE_CXX11_ABI && ! _GLIBCXX_INLINE_VERSION
   inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
 # endif
   }
@@ -445,6 +425,26 @@ _GLIBCXX_END_NAMESPACE_VERSION
 # endif
 #endif
 
+#if _GLIBCXX_USE_CXX11_ABI && ! _GLIBCXX_INLINE_VERSION
+namespace std
+{
+  inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
+}
+namespace __gnu_cxx
+{
+  inline namespace __cxx11 __attribute__((__abi_tag__ ("cxx11"))) { }
+}
+# define _GLIBCXX_NAMESPACE_CXX11 __cxx11::
+# define _GLIBCXX_BEGIN_NAMESPACE_CXX11 namespace __cxx11 {
+# define _GLIBCXX_END_NAMESPACE_CXX11 }
+# define _GLIBCXX_DEFAULT_ABI_TAG _GLIBCXX_ABI_TAG_CXX11
+#else
+# define _GLIBCXX_NAMESPACE_CXX11
+# define _GLIBCXX_BEGIN_NAMESPACE_CXX11
+# define _GLIBCXX_END_NAMESPACE_CXX11
+# define _GLIBCXX_DEFAULT_ABI_TAG
+#endif
+
 // Macros for namespace scope. Either namespace std:: or the name
 // of some nested namespace within it corresponding to the active mode.
 // _GLIBCXX_STD_A
diff --git a/libstdc++-v3/include/bits/cow_string.h b/libstdc++-v3/include/bits/cow_string.h
index e5f094fd13e..d5b98d30a70 100644
--- a/libstdc++-v3/include/bits/cow_string.h
+++ b/libstdc++-v3/include/bits/cow_string.h
@@ -32,8 +32,6 @@
 #ifndef _COW_STRING_H
 #define _COW_STRING_H 1
 
-#if ! _GLIBCXX_USE_CXX11_ABI
-
 #include <ext/atomicity.h> // _Atomic_word, __is_single_threaded
 
 #ifdef __cpp_lib_is_constant_evaluated
@@ -44,6 +42,10 @@
 # define __cpp_lib_constexpr_string 201611L
 #endif
 
+#if _GLIBCXX_USE_CXX11_ABI
+# define basic_string __std_cow_string
+#endif
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -835,6 +837,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       end() const _GLIBCXX_NOEXCEPT
       { return const_iterator(_M_data() + this->size()); }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  Returns a read/write reverse iterator that points to the last
        *  character in the %string.  Iteration is done in reverse element
@@ -906,6 +909,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       crend() const noexcept
       { return const_reverse_iterator(this->begin()); }
 #endif
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
     public:
       // Capacity:
@@ -933,6 +937,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       max_size() const _GLIBCXX_NOEXCEPT
       { return _Rep::_S_max_size; }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  @brief  Resizes the %string to the specified number of characters.
        *  @param  __n  Number of characters the %string should contain.
@@ -969,7 +974,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { reserve(); }
 #pragma GCC diagnostic pop
 #endif
-
+#endif // ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  Returns the total number of characters that the %string can hold
        *  before needing to allocate more memory.
@@ -978,6 +983,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       capacity() const _GLIBCXX_NOEXCEPT
       { return _M_rep()->_M_capacity; }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  @brief  Attempt to preallocate enough memory for specified number of
        *          characters.
@@ -1026,6 +1032,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       clear()
       { _M_mutate(0, this->size(), 0); }
 #endif
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
       /**
        *  Returns true if the %string is empty.  Equivalent to
@@ -1035,6 +1042,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       empty() const _GLIBCXX_NOEXCEPT
       { return this->size() == 0; }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       // Element access:
       /**
        *  @brief  Subscript access to the data contained in the %string.
@@ -1345,6 +1353,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	traits_type::assign(_M_data()[this->size()], __c);
 	_M_rep()->_M_set_length_and_sharable(__len);
       }
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
       /**
        *  @brief  Set value to contents of another string.
@@ -1489,6 +1498,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	}
 #endif // C++17
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  @brief  Insert multiple characters.
        *  @param __p  Iterator referencing location in string to insert at.
@@ -2107,6 +2117,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  return this->replace(__i1 - begin(), __i2 - __i1, __sv);
 	}
 #endif // C++17
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
     private:
       template<class _Integer>
@@ -2178,6 +2189,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     public:
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  @brief  Copy substring into C string.
        *  @param __s  C string to copy value into.
@@ -2192,6 +2204,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       */
       size_type
       copy(_CharT* __s, size_type __n, size_type __pos = 0) const;
+#endif
 
       /**
        *  @brief  Swap contents with another string.
@@ -2249,6 +2262,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       get_allocator() const _GLIBCXX_NOEXCEPT
       { return _M_dataplus; }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
       /**
        *  @brief  Find position of a C substring.
        *  @param __s  C string to locate.
@@ -3054,6 +3068,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       contains(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).contains(__x); }
 #endif // C++23
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
 # ifdef _GLIBCXX_TM_TS_INTERNAL
       friend void
@@ -3257,6 +3272,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	}
      }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   template<typename _CharT, typename _Traits, typename _Alloc>
     basic_string<_CharT, _Traits, _Alloc>&
     basic_string<_CharT, _Traits, _Alloc>::
@@ -3420,6 +3436,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	   return _M_replace_safe(__pos, __n1, __tmp._M_data(), __n2);
 	 }
      }
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
   template<typename _CharT, typename _Traits, typename _Alloc>
     void
@@ -3481,6 +3498,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _M_rep()->_M_set_length_and_sharable(__new_size);
     }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   template<typename _CharT, typename _Traits, typename _Alloc>
     void
     basic_string<_CharT, _Traits, _Alloc>::
@@ -3506,6 +3524,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _M_rep()->_M_dispose(__a);
       _M_data(__tmp);
     }
+#endif
 
   template<typename _CharT, typename _Traits, typename _Alloc>
     void
@@ -3629,6 +3648,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return __r->_M_refdata();
     }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   template<typename _CharT, typename _Traits, typename _Alloc>
     void
     basic_string<_CharT, _Traits, _Alloc>::
@@ -3642,6 +3662,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	this->erase(__n);
       // else nothing (in particular, avoid calling _M_mutate() unnecessarily.)
     }
+  #endif
 
   template<typename _CharT, typename _Traits, typename _Alloc>
     template<typename _InputIterator>
@@ -3682,6 +3703,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return *this;
     }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   template<typename _CharT, typename _Traits, typename _Alloc>
     void
     basic_string<_CharT, _Traits, _Alloc>::
@@ -3716,7 +3738,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // 21.3.5.7 par 3: do not append null.  (good.)
       return __n;
     }
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
-#endif  // ! _GLIBCXX_USE_CXX11_ABI
+
+#if _GLIBCXX_USE_CXX11_ABI
+# undef basic_string
+#endif
 #endif  // _COW_STRING_H
diff --git a/libstdc++-v3/include/std/stdexcept b/libstdc++-v3/include/std/stdexcept
index 66c8572d0cd..33306508695 100644
--- a/libstdc++-v3/include/std/stdexcept
+++ b/libstdc++-v3/include/std/stdexcept
@@ -42,8 +42,8 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-#if _GLIBCXX_USE_DUAL_ABI
-#if _GLIBCXX_USE_CXX11_ABI
+#if _GLIBCXX_USE_DUAL_ABI || _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_DEFINE_STDEXCEPT_INSTANTIATIONS
   // Emulates an old COW string when the new std::string is in use.
   struct __cow_string
   {
@@ -54,6 +54,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     __cow_string();
     __cow_string(const std::string&);
+    __cow_string(const char*);
     __cow_string(const char*, size_t);
     __cow_string(const __cow_string&) _GLIBCXX_NOTHROW;
     __cow_string& operator=(const __cow_string&) _GLIBCXX_NOTHROW;
@@ -62,12 +63,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __cow_string(__cow_string&&) noexcept;
     __cow_string& operator=(__cow_string&&) noexcept;
 #endif
+    const char* c_str() const _GLIBCXX_NOEXCEPT;
   };
-
-  typedef basic_string<char> __sso_string;
-#else // _GLIBCXX_USE_CXX11_ABI
+#endif // ! _GLIBCXX_DEFINE_STDEXCEPT_INSTANTIATIONS
+#else
   typedef basic_string<char> __cow_string;
+#endif
 
+#if _GLIBCXX_USE_DUAL_ABI && ! _GLIBCXX_USE_CXX11_ABI
   // Emulates a new SSO string when the old std::string is in use.
   struct __sso_string
   {
@@ -94,10 +97,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __sso_string& operator=(__sso_string&&) noexcept;
 #endif
   };
-#endif // _GLIBCXX_USE_CXX11_ABI
-#else  // _GLIBCXX_USE_DUAL_ABI
+#else
   typedef basic_string<char> __sso_string;
-  typedef basic_string<char> __cow_string;
 #endif
 
   /**
@@ -127,7 +128,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     logic_error& operator=(logic_error&&) noexcept;
 #endif
 
-#if _GLIBCXX_USE_CXX11_ABI || _GLIBCXX_DEFINE_STDEXCEPT_COPY_OPS
+#if _GLIBCXX_USE_CXX11_ABI || _GLIBCXX_DEFINE_STDEXCEPT_INSTANTIATIONS
     logic_error(const logic_error&) _GLIBCXX_NOTHROW;
     logic_error& operator=(const logic_error&) _GLIBCXX_NOTHROW;
 #elif __cplusplus >= 201103L
@@ -233,7 +234,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     runtime_error& operator=(runtime_error&&) noexcept;
 #endif
 
-#if _GLIBCXX_USE_CXX11_ABI || _GLIBCXX_DEFINE_STDEXCEPT_COPY_OPS
+#if _GLIBCXX_USE_CXX11_ABI || _GLIBCXX_DEFINE_STDEXCEPT_INSTANTIATIONS
     runtime_error(const runtime_error&) _GLIBCXX_NOTHROW;
     runtime_error& operator=(const runtime_error&) _GLIBCXX_NOTHROW;
 #elif __cplusplus >= 201103L
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index b4c427d487c..a43bf105308 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -963,6 +963,8 @@ class StdStringPrinter:
     def __init__(self, typename, val):
         self.val = val
         self.new_string = typename.find("::__cxx11::basic_string") != -1
+        if not self.new_string and _versioned_namespace:
+            self.new_string = typename.find("::" + _versioned_namespace + "basic_string") != -1
 
     def to_string(self):
         # Make sure &string works, too.
diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index 5b9af41cdb9..ec0c502ecb1 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -89,6 +89,9 @@ else
 ldbl_compat_sources =
 endif
 
+if ENABLE_SYMVERS_GNU_NAMESPACE
+ldbl_alt128_compat_sources =
+else
 if GLIBCXX_LDBL_ALT128_COMPAT
 if ENABLE_DUAL_ABI
 ldbl_alt128_compat_cxx11_sources = \
@@ -102,6 +105,7 @@ ldbl_alt128_compat_sources = \
 else
 ldbl_alt128_compat_sources =
 endif
+endif
 
 if ENABLE_SYMVERS_GNU_NAMESPACE
 cxx0x_compat_sources =
diff --git a/libstdc++-v3/src/Makefile.in b/libstdc++-v3/src/Makefile.in
index f42d957af36..c9c1b65db52 100644
--- a/libstdc++-v3/src/Makefile.in
+++ b/libstdc++-v3/src/Makefile.in
@@ -157,10 +157,9 @@ am__objects_2 = compatibility.lo compatibility-debug_list.lo \
 @ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@	compatibility-chrono.lo \
 @ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@	compatibility-condvar.lo \
 @ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@	compatibility-thread-c++0x.lo
-@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@am__objects_4 = compatibility-ldbl-alt128-cxx11.lo
-@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@am__objects_5 =  \
-@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128.lo \
-@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(am__objects_4)
+@ENABLE_DUAL_ABI_TRUE@@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@am__objects_4 = compatibility-ldbl-alt128-cxx11.lo
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@am__objects_5 = compatibility-ldbl-alt128.lo \
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(am__objects_4)
 am__objects_6 = $(am__objects_3) $(am__objects_5)
 @GLIBCXX_HOSTED_TRUE@am_libstdc___la_OBJECTS = $(am__objects_2) \
 @GLIBCXX_HOSTED_TRUE@	$(am__objects_6)
@@ -510,14 +509,15 @@ SUBDIRS = c++98 c++11 c++17 c++20 $(filesystem_dir) $(backtrace_dir) $(experimen
 
 @GLIBCXX_LDBL_COMPAT_FALSE@ldbl_compat_sources = 
 @GLIBCXX_LDBL_COMPAT_TRUE@ldbl_compat_sources = compatibility-ldbl.cc
-@ENABLE_DUAL_ABI_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_cxx11_sources = 
-@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_cxx11_sources = \
-@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128-cxx11.cc
-
-@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@ldbl_alt128_compat_sources = 
-@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_sources = \
-@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128.cc \
-@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	${ldbl_alt128_compat_cxx11_sources}
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@ldbl_alt128_compat_sources = 
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_sources = \
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128.cc \
+@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	${ldbl_alt128_compat_cxx11_sources}
+
+@ENABLE_SYMVERS_GNU_NAMESPACE_TRUE@ldbl_alt128_compat_sources = 
+@ENABLE_DUAL_ABI_FALSE@@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_cxx11_sources = 
+@ENABLE_DUAL_ABI_TRUE@@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_cxx11_sources = \
+@ENABLE_DUAL_ABI_TRUE@@ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128-cxx11.cc
 
 @ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@cxx0x_compat_sources = \
 @ENABLE_SYMVERS_GNU_NAMESPACE_FALSE@	compatibility-atomic-c++0x.cc \
diff --git a/libstdc++-v3/src/c++11/Makefile.am b/libstdc++-v3/src/c++11/Makefile.am
index 682be1669a4..82227338798 100644
--- a/libstdc++-v3/src/c++11/Makefile.am
+++ b/libstdc++-v3/src/c++11/Makefile.am
@@ -40,15 +40,11 @@ ctype_members.cc: ${glibcxx_srcdir}/$(CCTYPE_CC)
 	$(LN_S) ${glibcxx_srcdir}/$(CCTYPE_CC) . || true
 
 if ENABLE_DUAL_ABI
-cxx11_abi_sources = \
-	cow-locale_init.cc \
+dual_abi_sources = \
 	cow-shim_facets.cc \
-	cxx11-hash_tr1.cc \
-	cxx11-ios_failure.cc \
-	cxx11-shim_facets.cc \
-	cxx11-stdexcept.cc
+	cxx11-shim_facets.cc
 else
-cxx11_abi_sources =
+dual_abi_sources =
 endif
 
 sources_freestanding = \
@@ -59,8 +55,12 @@ sources = \
 	chrono.cc \
 	codecvt.cc \
 	condition_variable.cc \
+	cow-locale_init.cc \
 	cow-stdexcept.cc \
 	ctype.cc \
+	cxx11-hash_tr1.cc \
+	cxx11-ios_failure.cc \
+	cxx11-stdexcept.cc \
 	debug.cc \
 	functexcept.cc \
 	functional.cc \
@@ -77,19 +77,11 @@ sources = \
 	snprintf_lite.cc \
 	system_error.cc \
 	thread.cc \
-	${cxx11_abi_sources} \
+	${dual_abi_sources} \
 	${host_sources}
 
 if ENABLE_DUAL_ABI
 extra_string_inst_sources = \
-	cow-fstream-inst.cc \
-	cow-sstream-inst.cc \
-	cow-string-inst.cc \
-	cow-string-io-inst.cc \
-	cow-wstring-inst.cc \
-	cow-wstring-io-inst.cc \
-	cxx11-locale-inst.cc \
-	cxx11-wlocale-inst.cc \
 	sso_string.cc
 else
 extra_string_inst_sources =
@@ -99,6 +91,14 @@ if ENABLE_EXTERN_TEMPLATE
 # XTEMPLATE_FLAGS = -fno-implicit-templates
 inst_sources = \
 	$(extra_string_inst_sources) \
+	cow-fstream-inst.cc \
+	cow-sstream-inst.cc \
+	cow-string-inst.cc \
+	cow-string-io-inst.cc \
+	cow-wstring-inst.cc \
+	cow-wstring-io-inst.cc \
+	cxx11-locale-inst.cc \
+	cxx11-wlocale-inst.cc \
 	ext11-inst.cc \
 	fstream-inst.cc \
 	ios-inst.cc \
diff --git a/libstdc++-v3/src/c++11/Makefile.in b/libstdc++-v3/src/c++11/Makefile.in
index e7a09fe3246..2d94425480b 100644
--- a/libstdc++-v3/src/c++11/Makefile.in
+++ b/libstdc++-v3/src/c++11/Makefile.in
@@ -122,25 +122,26 @@ CONFIG_CLEAN_VPATH_FILES =
 LTLIBRARIES = $(noinst_LTLIBRARIES)
 libc__11convenience_la_LIBADD =
 am__objects_1 = limits.lo placeholders.lo
-@ENABLE_DUAL_ABI_TRUE@am__objects_2 = cow-locale_init.lo \
-@ENABLE_DUAL_ABI_TRUE@	cow-shim_facets.lo cxx11-hash_tr1.lo \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-ios_failure.lo \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-shim_facets.lo cxx11-stdexcept.lo
+@ENABLE_DUAL_ABI_TRUE@am__objects_2 = cow-shim_facets.lo \
+@ENABLE_DUAL_ABI_TRUE@	cxx11-shim_facets.lo
 am__objects_3 = ctype_configure_char.lo ctype_members.lo
 am__objects_4 = chrono.lo codecvt.lo condition_variable.lo \
-	cow-stdexcept.lo ctype.lo debug.lo functexcept.lo \
-	functional.lo futex.lo future.lo hash_c++0x.lo \
+	cow-locale_init.lo cow-stdexcept.lo ctype.lo cxx11-hash_tr1.lo \
+	cxx11-ios_failure.lo cxx11-stdexcept.lo debug.lo \
+	functexcept.lo functional.lo futex.lo future.lo hash_c++0x.lo \
 	hashtable_c++0x.lo ios.lo ios_errcat.lo mutex.lo random.lo \
 	regex.lo shared_ptr.lo snprintf_lite.lo system_error.lo \
 	thread.lo $(am__objects_2) $(am__objects_3)
-@ENABLE_DUAL_ABI_TRUE@am__objects_5 = cow-fstream-inst.lo \
-@ENABLE_DUAL_ABI_TRUE@	cow-sstream-inst.lo cow-string-inst.lo \
-@ENABLE_DUAL_ABI_TRUE@	cow-string-io-inst.lo \
-@ENABLE_DUAL_ABI_TRUE@	cow-wstring-inst.lo \
-@ENABLE_DUAL_ABI_TRUE@	cow-wstring-io-inst.lo \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-locale-inst.lo \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-wlocale-inst.lo sso_string.lo
+@ENABLE_DUAL_ABI_TRUE@am__objects_5 = sso_string.lo
 @ENABLE_EXTERN_TEMPLATE_TRUE@am__objects_6 = $(am__objects_5) \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-fstream-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-sstream-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-string-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-string-io-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-wstring-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-wstring-io-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cxx11-locale-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cxx11-wlocale-inst.lo \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	ext11-inst.lo fstream-inst.lo \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	ios-inst.lo iostream-inst.lo \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	istream-inst.lo locale-inst.lo \
@@ -461,14 +462,10 @@ host_sources = \
 	ctype_configure_char.cc \
 	ctype_members.cc
 
-@ENABLE_DUAL_ABI_FALSE@cxx11_abi_sources = 
-@ENABLE_DUAL_ABI_TRUE@cxx11_abi_sources = \
-@ENABLE_DUAL_ABI_TRUE@	cow-locale_init.cc \
+@ENABLE_DUAL_ABI_FALSE@dual_abi_sources = 
+@ENABLE_DUAL_ABI_TRUE@dual_abi_sources = \
 @ENABLE_DUAL_ABI_TRUE@	cow-shim_facets.cc \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-hash_tr1.cc \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-ios_failure.cc \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-shim_facets.cc \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-stdexcept.cc
+@ENABLE_DUAL_ABI_TRUE@	cxx11-shim_facets.cc
 
 sources_freestanding = \
 	limits.cc \
@@ -478,8 +475,12 @@ sources = \
 	chrono.cc \
 	codecvt.cc \
 	condition_variable.cc \
+	cow-locale_init.cc \
 	cow-stdexcept.cc \
 	ctype.cc \
+	cxx11-hash_tr1.cc \
+	cxx11-ios_failure.cc \
+	cxx11-stdexcept.cc \
 	debug.cc \
 	functexcept.cc \
 	functional.cc \
@@ -496,19 +497,11 @@ sources = \
 	snprintf_lite.cc \
 	system_error.cc \
 	thread.cc \
-	${cxx11_abi_sources} \
+	${dual_abi_sources} \
 	${host_sources}
 
 @ENABLE_DUAL_ABI_FALSE@extra_string_inst_sources = 
 @ENABLE_DUAL_ABI_TRUE@extra_string_inst_sources = \
-@ENABLE_DUAL_ABI_TRUE@	cow-fstream-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cow-sstream-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cow-string-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cow-string-io-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cow-wstring-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cow-wstring-io-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-locale-inst.cc \
-@ENABLE_DUAL_ABI_TRUE@	cxx11-wlocale-inst.cc \
 @ENABLE_DUAL_ABI_TRUE@	sso_string.cc
 
 # XTEMPLATE_FLAGS =
@@ -517,6 +510,14 @@ sources = \
 # XTEMPLATE_FLAGS = -fno-implicit-templates
 @ENABLE_EXTERN_TEMPLATE_TRUE@inst_sources = \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	$(extra_string_inst_sources) \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-fstream-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-sstream-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-string-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-string-io-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-wstring-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cow-wstring-io-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cxx11-locale-inst.cc \
+@ENABLE_EXTERN_TEMPLATE_TRUE@	cxx11-wlocale-inst.cc \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	ext11-inst.cc \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	fstream-inst.cc \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	ios-inst.cc \
diff --git a/libstdc++-v3/src/c++11/cow-fstream-inst.cc b/libstdc++-v3/src/c++11/cow-fstream-inst.cc
index 0562bc6c9cb..8153387daea 100644
--- a/libstdc++-v3/src/c++11/cow-fstream-inst.cc
+++ b/libstdc++-v3/src/c++11/cow-fstream-inst.cc
@@ -29,10 +29,7 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include <fstream>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
-
+#if ! _GLIBCXX_USE_CXX11_ABI
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -76,3 +73,4 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+#endif
diff --git a/libstdc++-v3/src/c++11/cow-locale_init.cc b/libstdc++-v3/src/c++11/cow-locale_init.cc
index 85277763427..6833f903f47 100644
--- a/libstdc++-v3/src/c++11/cow-locale_init.cc
+++ b/libstdc++-v3/src/c++11/cow-locale_init.cc
@@ -24,10 +24,7 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include <locale>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
-
+#if ! _GLIBCXX_USE_CXX11_ABI
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -165,6 +162,7 @@ namespace
 #endif
   }
 
+#if _GLIBCXX_USE_DUAL_ABI
 // TODO should be in another file
   string
   locale::name() const
@@ -190,6 +188,8 @@ namespace
       }
     return __ret;
   }
+#endif
 
 _GLIBCXX_END_NAMESPACE_VERSION
 }
+#endif // ! _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++11/cow-sstream-inst.cc b/libstdc++-v3/src/c++11/cow-sstream-inst.cc
index 035a267d9d8..7699170d13d 100644
--- a/libstdc++-v3/src/c++11/cow-sstream-inst.cc
+++ b/libstdc++-v3/src/c++11/cow-sstream-inst.cc
@@ -27,8 +27,8 @@
 //
 
 #define _GLIBCXX_USE_CXX11_ABI 0
-#include "sstream-inst.cc"
+#include <bits/c++config.h>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
+#if ! _GLIBCXX_USE_CXX11_ABI
+# include "sstream-inst.cc"
 #endif
diff --git a/libstdc++-v3/src/c++11/cow-stdexcept.cc b/libstdc++-v3/src/c++11/cow-stdexcept.cc
index 8d1cc4605d4..23f853eadac 100644
--- a/libstdc++-v3/src/c++11/cow-stdexcept.cc
+++ b/libstdc++-v3/src/c++11/cow-stdexcept.cc
@@ -43,11 +43,52 @@ _txnal_runtime_error_get_msg(void* e);
 
 // All exception classes still use the classic COW std::string.
 #define _GLIBCXX_USE_CXX11_ABI 0
-#define _GLIBCXX_DEFINE_STDEXCEPT_COPY_OPS 1
-#define __cow_string __cow_stringxxx
+#include <string>
+
+#if _GLIBCXX_USE_DUAL_ABI || _GLIBCXX_USE_CXX11_ABI
+# if _GLIBCXX_USE_CXX11_ABI
+#  include <bits/cow_string.h>
+# endif
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+# if _GLIBCXX_USE_CXX11_ABI
+  typedef std::__std_cow_string<char, std::char_traits<char>,
+				std::allocator<char>> cowstr;
+# else
+  typedef std::string cowstr;
+# endif
+
+  // Redefine __cow_string so that we can define and export its members
+  // in terms of the COW std::string.
+  struct __cow_string
+  {
+    union {
+      const char* _M_p;
+      char _M_bytes[sizeof(_M_p)];
+      cowstr _M_str;
+    };
+
+    __cow_string();
+    __cow_string(const std::string& s);
+    __cow_string(const char*);
+    __cow_string(const char*, size_t);
+    __cow_string(const __cow_string&) noexcept;
+    __cow_string& operator=(const __cow_string&) noexcept;
+    ~__cow_string();
+    __cow_string(__cow_string&&) noexcept;
+    __cow_string& operator=(__cow_string&&) noexcept;
+    const char* c_str() const noexcept;
+  };
+_GLIBCXX_END_NAMESPACE_VERSION
+}
+#endif
+
+#define _GLIBCXX_DEFINE_STDEXCEPT_INSTANTIATIONS 1
 #include <stdexcept>
 #include <system_error>
-#undef __cow_string
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
@@ -114,30 +155,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Converting constructor from COW std::string to SSO string.
   __sso_string::__sso_string(const string& s)
   : __sso_string(s.c_str(), s.length()) { }
+#endif
 
-  // Redefine __cow_string so that we can define and export its members
-  // in terms of the COW std::string.
-  struct __cow_string
-  {
-    union {
-      const char* _M_p;
-      char _M_bytes[sizeof(_M_p)];
-      std::string _M_str;
-    };
-
-    __cow_string();
-    __cow_string(const std::string& s);
-    __cow_string(const char*, size_t n);
-    __cow_string(const __cow_string&) noexcept;
-    __cow_string& operator=(const __cow_string&) noexcept;
-    ~__cow_string();
-    __cow_string(__cow_string&&) noexcept;
-    __cow_string& operator=(__cow_string&&) noexcept;
-  };
-
+#if _GLIBCXX_USE_DUAL_ABI || _GLIBCXX_USE_CXX11_ABI
   __cow_string::__cow_string() : _M_str() { }
 
+#if !_GLIBCXX_USE_CXX11_ABI
   __cow_string::__cow_string(const std::string& s) : _M_str(s) { }
+#endif
+
+  __cow_string::__cow_string(const char* s) : _M_str(s) { }
 
   __cow_string::__cow_string(const char* s, size_t n) : _M_str(s, n) { }
 
@@ -151,7 +178,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     return *this;
   }
 
-  __cow_string::~__cow_string() { _M_str.~basic_string(); }
+  __cow_string::~__cow_string() { _M_str.~cowstr(); }
 
   __cow_string::__cow_string(__cow_string&& s) noexcept
   : _M_str(std::move(s._M_str)) { }
@@ -163,12 +190,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     return *this;
   }
 
-  static_assert(sizeof(__cow_string) == sizeof(std::string),
+  const char*
+  __cow_string::c_str() const noexcept
+  { return _M_str.c_str(); }
+
+  static_assert(sizeof(__cow_string) == sizeof(cowstr),
                 "sizeof(std::string) has changed");
-  static_assert(alignof(__cow_string) == alignof(std::string),
+  static_assert(alignof(__cow_string) == alignof(cowstr),
                 "alignof(std::string) has changed");
-#endif
+#endif // _GLIBCXX_USE_CXX11_ABI
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   // Return error_category::message() as an SSO string
   __sso_string
   error_category::_M_message(int i) const
@@ -176,10 +208,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     string msg = this->message(i);
     return {msg.c_str(), msg.length()};
   }
+#endif
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 
+#if ! _GLIBCXX_USE_CXX11_ABI
 // Support for the Transactional Memory TS (N4514).
 //
 // logic_error and runtime_error both carry a message in the form of a COW
@@ -463,3 +497,4 @@ CTORDTOR(15underflow_error, std::underflow_error, runtime_error)
 
 #endif  // _GLIBCXX_USE_C99_STDINT
 #endif  // _GLIBCXX_USE_WEAK_REF
+#endif  // ! _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++11/cow-string-inst.cc b/libstdc++-v3/src/c++11/cow-string-inst.cc
index 5a2b8ffa568..57c28129f00 100644
--- a/libstdc++-v3/src/c++11/cow-string-inst.cc
+++ b/libstdc++-v3/src/c++11/cow-string-inst.cc
@@ -29,10 +29,7 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include "string-inst.cc"
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
-
+#if _GLIBCXX_USE_DUAL_ABI && ! _GLIBCXX_USE_CXX11_ABI
 #include <random>
 
 namespace std _GLIBCXX_VISIBILITY(default)
@@ -45,3 +42,4 @@ namespace std _GLIBCXX_VISIBILITY(default)
   random_device::_M_init_pretr1(const std::string& token)
   { _M_init(token.c_str(), token.length()); }
 } // namespace
+#endif
diff --git a/libstdc++-v3/src/c++11/cow-string-io-inst.cc b/libstdc++-v3/src/c++11/cow-string-io-inst.cc
index 505bc9dd384..9abc9b47e52 100644
--- a/libstdc++-v3/src/c++11/cow-string-io-inst.cc
+++ b/libstdc++-v3/src/c++11/cow-string-io-inst.cc
@@ -30,10 +30,7 @@
 #include <istream>
 #include <ostream>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
-
+#if ! _GLIBCXX_USE_CXX11_ABI
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -57,3 +54,4 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+#endif
diff --git a/libstdc++-v3/src/c++11/cow-wstring-inst.cc b/libstdc++-v3/src/c++11/cow-wstring-inst.cc
index ce533ea8fa5..d3c3b0c297e 100644
--- a/libstdc++-v3/src/c++11/cow-wstring-inst.cc
+++ b/libstdc++-v3/src/c++11/cow-wstring-inst.cc
@@ -29,12 +29,9 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include <bits/c++config.h>
 
+#if ! _GLIBCXX_USE_CXX11_ABI
 #ifdef _GLIBCXX_USE_WCHAR_T
 #define C wchar_t
 #include "string-inst.cc"
-
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
 #endif
-
 #endif
diff --git a/libstdc++-v3/src/c++11/cow-wstring-io-inst.cc b/libstdc++-v3/src/c++11/cow-wstring-io-inst.cc
index 49394b0e275..0e6cc490fa4 100644
--- a/libstdc++-v3/src/c++11/cow-wstring-io-inst.cc
+++ b/libstdc++-v3/src/c++11/cow-wstring-io-inst.cc
@@ -29,14 +29,11 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include <bits/c++config.h>
 
+#if ! _GLIBCXX_USE_CXX11_ABI
 #ifdef _GLIBCXX_USE_WCHAR_T
 #include <ostream>
 #include <istream>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
-
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -61,3 +58,4 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 #endif
+#endif
diff --git a/libstdc++-v3/src/c++11/cxx11-hash_tr1.cc b/libstdc++-v3/src/c++11/cxx11-hash_tr1.cc
index 22a7685eeca..0b9fc28ceaa 100644
--- a/libstdc++-v3/src/c++11/cxx11-hash_tr1.cc
+++ b/libstdc++-v3/src/c++11/cxx11-hash_tr1.cc
@@ -25,9 +25,7 @@
 #define _GLIBCXX_USE_CXX11_ABI 1
 #include <string>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
+#if _GLIBCXX_USE_CXX11_ABI
 
 #include <tr1/functional>
 namespace std _GLIBCXX_VISIBILITY(default)
@@ -57,3 +55,5 @@ namespace std _GLIBCXX_VISIBILITY(default)
 #endif
   }
 }
+
+#endif // _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++11/cxx11-ios_failure.cc b/libstdc++-v3/src/c++11/cxx11-ios_failure.cc
index e0e816b453b..46bfda329de 100644
--- a/libstdc++-v3/src/c++11/cxx11-ios_failure.cc
+++ b/libstdc++-v3/src/c++11/cxx11-ios_failure.cc
@@ -38,9 +38,7 @@
 # define _(msgid)   (msgid)
 #endif
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
+#if _GLIBCXX_USE_CXX11_ABI
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
@@ -62,7 +60,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   ios_base::failure::what() const throw()
   { return runtime_error::what(); }
 
-#if __cpp_rtti
+#if _GLIBCXX_USE_DUAL_ABI && __cpp_rtti
   // These functions are defined in src/c++98/ios_failure.cc
   extern void __construct_ios_failure(void*, const char*);
   extern void __destroy_ios_failure(void*);
@@ -118,7 +116,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     // Otherwise proceed as normal to see if the handler matches.
     return __class_type_info::__do_upcast(dst_type, obj_ptr);
   }
-#else // ! __cpp_rtti
+#else // ! _GLIBCXX_USE_DUAL_ABI || ! __cpp_rtti
   using __ios_failure = ios::failure;
 #endif
 
@@ -136,3 +134,5 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+
+#endif // _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++11/cxx11-locale-inst.cc b/libstdc++-v3/src/c++11/cxx11-locale-inst.cc
index 94b181886d3..e21cc5548bf 100644
--- a/libstdc++-v3/src/c++11/cxx11-locale-inst.cc
+++ b/libstdc++-v3/src/c++11/cxx11-locale-inst.cc
@@ -27,11 +27,5 @@
 // Facet instantiations using new ABI strings.
 
 #define _GLIBCXX_USE_CXX11_ABI 1
-#include <bits/c++config.h>
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
 
-#define C char
-#define C_is_char
-# include "locale-inst.cc"
+#include "locale-inst.cc"
diff --git a/libstdc++-v3/src/c++11/cxx11-stdexcept.cc b/libstdc++-v3/src/c++11/cxx11-stdexcept.cc
index 74c070c0439..25236a79950 100644
--- a/libstdc++-v3/src/c++11/cxx11-stdexcept.cc
+++ b/libstdc++-v3/src/c++11/cxx11-stdexcept.cc
@@ -29,9 +29,7 @@
 #define _GLIBCXX_USE_CXX11_ABI 1
 #include <stdexcept>
 
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
+#if _GLIBCXX_USE_CXX11_ABI
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
@@ -70,9 +68,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   underflow_error::underflow_error(const string& __arg)
   : runtime_error(__arg) { }
 
+#if _GLIBCXX_USE_DUAL_ABI
   // Converting constructor from ABI-tagged std::string to COW string.
   __cow_string::__cow_string(const string& s)
   : __cow_string(s.c_str(), s.length()) { }
+#endif
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+
+#endif // _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc b/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc
index 11fb15d9602..faff236c1df 100644
--- a/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc
+++ b/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc
@@ -28,11 +28,10 @@
 
 #define _GLIBCXX_USE_CXX11_ABI 1
 #include <bits/c++config.h>
-#if ! _GLIBCXX_USE_DUAL_ABI
-# error This file should not be compiled for this configuration.
-#endif
 
-#ifdef _GLIBCXX_USE_WCHAR_T
-#define C wchar_t
-#include "locale-inst.cc"
+#if _GLIBCXX_USE_CXX11_ABI
+# ifdef _GLIBCXX_USE_WCHAR_T
+#  define C wchar_t
+#  include "locale-inst.cc"
+# endif
 #endif
diff --git a/libstdc++-v3/src/c++11/locale-inst-numeric.h b/libstdc++-v3/src/c++11/locale-inst-numeric.h
index b917fe5802e..211e19c7ff9 100644
--- a/libstdc++-v3/src/c++11/locale-inst-numeric.h
+++ b/libstdc++-v3/src/c++11/locale-inst-numeric.h
@@ -30,7 +30,7 @@
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 // use_facet and has_facet instantiations
 INSTANTIATE_FACET_ACCESSORS(num_get<C>);
 INSTANTIATE_FACET_ACCESSORS(num_put<C>);
@@ -38,7 +38,7 @@ INSTANTIATE_FACET_ACCESSORS(num_put<C>);
 
 _GLIBCXX_BEGIN_NAMESPACE_LDBL
 
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   template class num_get<C, istreambuf_iterator<C> >;
   template class num_put<C, ostreambuf_iterator<C> >;
 #endif
@@ -88,7 +88,7 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
 		   unsigned long long&) const;
 #endif
 
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   // num_put member function templates
   template
     ostreambuf_iterator<C>
diff --git a/libstdc++-v3/src/c++11/locale-inst.cc b/libstdc++-v3/src/c++11/locale-inst.cc
index 3a5c6844f1b..ee3375d7040 100644
--- a/libstdc++-v3/src/c++11/locale-inst.cc
+++ b/libstdc++-v3/src/c++11/locale-inst.cc
@@ -35,8 +35,17 @@
 # define _GLIBCXX_USE_CXX11_ABI 0
 #endif
 
-#include <locale>
+#if _GLIBCXX_USE_CXX11_ABI
+# define _GLIBCXX_BUILD_CXX11_ABI 1
+#else
+# define _GLIBCXX_BUILD_CXX11_ABI 0
+#endif
+
+#include <bits/c++config.h>
 
+#if _GLIBCXX_BUILD_CXX11_ABI == _GLIBCXX_USE_CXX11_ABI
+
+#include <locale>
 // Instantiation configuration.
 #ifndef C
 # define C char
@@ -52,7 +61,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // moneypunct, money_get, and money_put
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   template struct __moneypunct_cache<C, false>;
   template struct __moneypunct_cache<C, true>;
 #endif
@@ -64,7 +73,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 _GLIBCXX_END_NAMESPACE_CXX11
 
   // numpunct, numpunct_byname, num_get, and num_put
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   template struct __numpunct_cache<C>;
 #endif
 _GLIBCXX_BEGIN_NAMESPACE_CXX11
@@ -73,7 +82,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 _GLIBCXX_END_NAMESPACE_CXX11
 
   // time_get and time_put
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   template class __timepunct<C>;
   template struct __timepunct_cache<C>;
   template class time_put<C, ostreambuf_iterator<C> >;
@@ -97,13 +106,13 @@ _GLIBCXX_END_NAMESPACE_CXX11
   ctype_byname<C>::ctype_byname(const string& __s, size_t __refs)
   : ctype_byname(__s.c_str(), __refs) { }
 
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   inline template class __ctype_abstract_base<C>;
   template class ctype_byname<C>;
 #endif
 
   // codecvt
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   inline template class __codecvt_abstract_base<C, char, mbstate_t>;
   template class codecvt_byname<C, char, mbstate_t>;
 #else
@@ -118,7 +127,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 _GLIBCXX_END_NAMESPACE_CXX11
 
 // use_facet and has_facet instantiations
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 INSTANTIATE_FACET_ACCESSORS(ctype<C>);
 INSTANTIATE_FACET_ACCESSORS(codecvt<C, char, mbstate_t>);
 #endif
@@ -127,14 +136,14 @@ INSTANTIATE_FACET_ACCESSORS(numpunct<C>);
 INSTANTIATE_FACET_ACCESSORS(moneypunct<C, false>);
 // No explicit instantiation of has_facet<moneypunct<C, true>> for some reason.
 INSTANTIATE_USE_FACET      (moneypunct<C, true>);
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
 INSTANTIATE_FACET_ACCESSORS(__timepunct<C>);
 INSTANTIATE_FACET_ACCESSORS(time_put<C>);
 #endif
 INSTANTIATE_FACET_ACCESSORS(time_get<C>);
 INSTANTIATE_FACET_ACCESSORS(messages<C>);
 
-#if ! _GLIBCXX_USE_CXX11_ABI
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
   // locale functions.
   template
     C*
@@ -163,3 +172,5 @@ _GLIBCXX_END_NAMESPACE_VERSION
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && ! _GLIBCXX_USE_CXX11_ABI
 #include "compatibility-ldbl-facets-aliases.h"
 #endif // _GLIBCXX_LONG_DOUBLE_COMPAT
+
+#endif //  _GLIBCXX_BUILD_CXX11_ABI == _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++11/string-inst.cc b/libstdc++-v3/src/c++11/string-inst.cc
index ddaafc08199..f29176dfc88 100644
--- a/libstdc++-v3/src/c++11/string-inst.cc
+++ b/libstdc++-v3/src/c++11/string-inst.cc
@@ -35,6 +35,12 @@
 # define _GLIBCXX_USE_CXX11_ABI 1
 #endif
 
+#if _GLIBCXX_USE_CXX11_ABI
+# define _GLIBCXX_DEFINING_CXX11_ABI_INSTANTIATIONS 1
+#else
+# define _GLIBCXX_DEFINING_CXX11_ABI_INSTANTIATIONS 0
+#endif
+
 // Prevent the basic_string(const _CharT*, const _Alloc&) and
 // basic_string(size_type, _CharT, const _Alloc&) constructors from being
 // replaced by constrained function templates, so that we instantiate the
@@ -45,6 +51,29 @@
 
 #include <string>
 
+#if _GLIBCXX_USE_DUAL_ABI || _GLIBCXX_USE_CXX11_ABI
+#include <stdexcept>
+
+#if _GLIBCXX_USE_CXX11_ABI
+# include <bits/cow_string.h>
+typedef std::__std_cow_string<char, std::char_traits<char>,
+			      std::allocator<char>> cowstr;
+#else
+typedef std::string cowstr;
+#endif
+
+static_assert(sizeof(std::__cow_string) == sizeof(cowstr),
+	      "sizeof(std::string) has changed");
+static_assert(alignof(std::__cow_string) == alignof(cowstr),
+	      "alignof(std::string) has changed");
+#endif // _GLIBCXX_USE_DUAL_ABI || _GLIBCXX_USE_CXX11_ABI
+
+#if _GLIBCXX_USE_CXX11_ABI && ! _GLIBCXX_DEFINING_CXX11_ABI_INSTANTIATIONS
+# define _GLIBCXX_DEFINING_COW_STRING_INSTANTIATIONS 1
+# include <bits/cow_string.h>
+# define basic_string __std_cow_string
+#endif
+
 // Instantiation configuration.
 #ifndef C
 # define C char
@@ -54,12 +83,14 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-  typedef basic_string<C> S;
+typedef basic_string<C, std::char_traits<C>, std::allocator<C>> S;
 
-  template class basic_string<C>;
+  template class basic_string<C, std::char_traits<C>, std::allocator<C>>;
+#if ! _GLIBCXX_DEFINING_COW_STRING_INSTANTIATIONS
   template S operator+(const C*, const S&);
   template S operator+(C, const S&);
   template S operator+(const S&, const S&);
+#endif
 
   // Only one template keyword allowed here.
   // See core issue #46 (NAD)
@@ -73,7 +104,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template
     S::basic_string(S::iterator, S::iterator, const allocator<C>&);
 
-#if _GLIBCXX_USE_CXX11_ABI
+#if _GLIBCXX_USE_CXX11_ABI && ! _GLIBCXX_DEFINING_COW_STRING_INSTANTIATIONS
   template
     void
     S::_M_construct(S::iterator, S::iterator, forward_iterator_tag);
@@ -91,7 +122,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     void
     S::_M_construct(const C*, const C*, forward_iterator_tag);
 
-#else // !_GLIBCXX_USE_CXX11_ABI
+#else // ! _GLIBCXX_USE_CXX11_ABI || _GLIBCXX_DEFINING_COW_STRING_INSTANTIATIONS
 
   template
     C*
@@ -111,6 +142,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 
+#if ! _GLIBCXX_DEFINING_COW_STRING_INSTANTIATIONS
 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -121,3 +153,4 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+#endif
diff --git a/libstdc++-v3/src/c++11/wlocale-inst.cc b/libstdc++-v3/src/c++11/wlocale-inst.cc
index dc2d2349055..b5c798bfe64 100644
--- a/libstdc++-v3/src/c++11/wlocale-inst.cc
+++ b/libstdc++-v3/src/c++11/wlocale-inst.cc
@@ -30,7 +30,9 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include <bits/c++config.h>
 
-#ifdef _GLIBCXX_USE_WCHAR_T
-#define C wchar_t
-#include "locale-inst.cc"
-#endif // _GLIBCXX_USE_WCHAR_T
+#if ! _GLIBCXX_USE_CXX11_ABI
+# ifdef _GLIBCXX_USE_WCHAR_T
+#  define C wchar_t
+#  include "locale-inst.cc"
+# endif // _GLIBCXX_USE_WCHAR_T
+#endif
diff --git a/libstdc++-v3/src/c++98/Makefile.am b/libstdc++-v3/src/c++98/Makefile.am
index 284ffda3443..eb24325af67 100644
--- a/libstdc++-v3/src/c++98/Makefile.am
+++ b/libstdc++-v3/src/c++98/Makefile.am
@@ -90,13 +90,6 @@ c++locale.cc: ${glibcxx_srcdir}/$(CLOCALE_CC)
 basic_file.cc: ${glibcxx_srcdir}/$(BASIC_FILE_CC)
 	$(LN_S) ${glibcxx_srcdir}/$(BASIC_FILE_CC) ./$@ || true
 
-if ENABLE_DUAL_ABI
-cxx11_abi_sources = \
-	cow-istream-string.cc
-else
-cxx11_abi_sources =
-endif
-
 if ENABLE_EXTERN_TEMPLATE
 # XTEMPLATE_FLAGS = -fno-implicit-templates
 inst_sources = \
@@ -118,6 +111,7 @@ sources = \
 	mt_allocator.cc \
 	codecvt.cc \
 	complex_io.cc \
+	cow-istream-string.cc \
 	globals_io.cc \
 	hash_tr1.cc \
 	hashtable_tr1.cc \
@@ -142,7 +136,6 @@ sources = \
 	istream-string.cc \
 	streambuf.cc \
 	valarray.cc \
-	${cxx11_abi_sources} \
 	${host_sources} \
 	${host_sources_extra}
 
diff --git a/libstdc++-v3/src/c++98/Makefile.in b/libstdc++-v3/src/c++98/Makefile.in
index a100df77a6d..d2ed2a221f2 100644
--- a/libstdc++-v3/src/c++98/Makefile.in
+++ b/libstdc++-v3/src/c++98/Makefile.in
@@ -121,31 +121,30 @@ CONFIG_CLEAN_FILES =
 CONFIG_CLEAN_VPATH_FILES =
 LTLIBRARIES = $(noinst_LTLIBRARIES)
 libc__98convenience_la_LIBADD =
-@ENABLE_DUAL_ABI_TRUE@am__objects_1 = cow-istream-string.lo
-@ENABLE_DUAL_ABI_TRUE@am__objects_2 = collate_members_cow.lo \
+@ENABLE_DUAL_ABI_TRUE@am__objects_1 = collate_members_cow.lo \
 @ENABLE_DUAL_ABI_TRUE@	messages_members_cow.lo \
 @ENABLE_DUAL_ABI_TRUE@	monetary_members_cow.lo \
 @ENABLE_DUAL_ABI_TRUE@	numeric_members_cow.lo
-am__objects_3 = $(am__objects_2) codecvt_members.lo collate_members.lo \
+am__objects_2 = $(am__objects_1) codecvt_members.lo collate_members.lo \
 	messages_members.lo monetary_members.lo numeric_members.lo \
 	time_members.lo
-@ENABLE_EXTERN_TEMPLATE_TRUE@am__objects_4 = allocator-inst.lo \
+@ENABLE_EXTERN_TEMPLATE_TRUE@am__objects_3 = allocator-inst.lo \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	concept-inst.lo ext-inst.lo \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	misc-inst.lo
-am__objects_5 = parallel_settings.lo
-am__objects_6 = basic_file.lo c++locale.lo $(am__objects_4) \
-	$(am__objects_5)
-am__objects_7 = bitmap_allocator.lo pool_allocator.lo mt_allocator.lo \
-	codecvt.lo complex_io.lo globals_io.lo hash_tr1.lo \
-	hashtable_tr1.lo ios_failure.lo ios_init.lo ios_locale.lo \
-	list.lo list-aux.lo list-aux-2.lo list_associated.lo \
-	list_associated-2.lo locale.lo locale_init.lo locale_facets.lo \
-	localename.lo math_stubs_float.lo math_stubs_long_double.lo \
-	stdexcept.lo strstream.lo tree.lo istream.lo istream-string.lo \
-	streambuf.lo valarray.lo $(am__objects_1) $(am__objects_3) \
-	$(am__objects_6)
+am__objects_4 = parallel_settings.lo
+am__objects_5 = basic_file.lo c++locale.lo $(am__objects_3) \
+	$(am__objects_4)
+am__objects_6 = bitmap_allocator.lo pool_allocator.lo mt_allocator.lo \
+	codecvt.lo complex_io.lo cow-istream-string.lo globals_io.lo \
+	hash_tr1.lo hashtable_tr1.lo ios_failure.lo ios_init.lo \
+	ios_locale.lo list.lo list-aux.lo list-aux-2.lo \
+	list_associated.lo list_associated-2.lo locale.lo \
+	locale_init.lo locale_facets.lo localename.lo \
+	math_stubs_float.lo math_stubs_long_double.lo stdexcept.lo \
+	strstream.lo tree.lo istream.lo istream-string.lo streambuf.lo \
+	valarray.lo $(am__objects_2) $(am__objects_5)
 @GLIBCXX_HOSTED_TRUE@am_libc__98convenience_la_OBJECTS =  \
-@GLIBCXX_HOSTED_TRUE@	$(am__objects_7)
+@GLIBCXX_HOSTED_TRUE@	$(am__objects_6)
 libc__98convenience_la_OBJECTS = $(am_libc__98convenience_la_OBJECTS)
 AM_V_lt = $(am__v_lt_@AM_V@)
 am__v_lt_ = $(am__v_lt_@AM_DEFAULT_V@)
@@ -471,10 +470,6 @@ host_sources_extra = \
 	basic_file.cc c++locale.cc \
 	${inst_sources} ${parallel_sources}
 
-@ENABLE_DUAL_ABI_FALSE@cxx11_abi_sources = 
-@ENABLE_DUAL_ABI_TRUE@cxx11_abi_sources = \
-@ENABLE_DUAL_ABI_TRUE@	cow-istream-string.cc
-
 # XTEMPLATE_FLAGS =
 @ENABLE_EXTERN_TEMPLATE_FALSE@inst_sources = 
 
@@ -494,6 +489,7 @@ sources = \
 	mt_allocator.cc \
 	codecvt.cc \
 	complex_io.cc \
+	cow-istream-string.cc \
 	globals_io.cc \
 	hash_tr1.cc \
 	hashtable_tr1.cc \
@@ -518,7 +514,6 @@ sources = \
 	istream-string.cc \
 	streambuf.cc \
 	valarray.cc \
-	${cxx11_abi_sources} \
 	${host_sources} \
 	${host_sources_extra}
 
diff --git a/libstdc++-v3/src/c++98/cow-istream-string.cc b/libstdc++-v3/src/c++98/cow-istream-string.cc
index 405f9ecb781..f00cbc09f69 100644
--- a/libstdc++-v3/src/c++98/cow-istream-string.cc
+++ b/libstdc++-v3/src/c++98/cow-istream-string.cc
@@ -27,4 +27,8 @@
 //
 
 #define _GLIBCXX_USE_CXX11_ABI 0
-#include "istream-string.cc"
+#include <bits/c++config.h>
+
+#if ! _GLIBCXX_USE_CXX11_ABI
+# include "istream-string.cc"
+#endif
diff --git a/libstdc++-v3/src/c++98/hash_tr1.cc b/libstdc++-v3/src/c++98/hash_tr1.cc
index e132c01bf8e..a2cd2c509f3 100644
--- a/libstdc++-v3/src/c++98/hash_tr1.cc
+++ b/libstdc++-v3/src/c++98/hash_tr1.cc
@@ -28,6 +28,7 @@
 
 #include "hash-long-double-tr1-aux.cc"
 
+#if ! _GLIBCXX_USE_CXX11_ABI
 namespace std _GLIBCXX_VISIBILITY(default)
 {
   namespace tr1
@@ -57,3 +58,4 @@ namespace std _GLIBCXX_VISIBILITY(default)
 #endif
   }
 }
+#endif // ! _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++98/ios_failure.cc b/libstdc++-v3/src/c++98/ios_failure.cc
index 27476eccbdb..43291871196 100644
--- a/libstdc++-v3/src/c++98/ios_failure.cc
+++ b/libstdc++-v3/src/c++98/ios_failure.cc
@@ -29,22 +29,24 @@
 #define _GLIBCXX_USE_CXX11_ABI 0
 #include <ios>
 
-#if _GLIBCXX_USE_DUAL_ABI && __cpp_rtti
-#include <cxxabi.h>
-#include <typeinfo>
-#endif
-
-#ifdef _GLIBCXX_USE_NLS
-# include <libintl.h>
-# define _(msgid)   gettext (msgid)
-#else
-# define _(msgid)   (msgid)
-#endif
+#if ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
+# if _GLIBCXX_USE_DUAL_ABI && __cpp_rtti
+#  include <cxxabi.h>
+#  include <typeinfo>
+# endif
+
+# ifdef _GLIBCXX_USE_NLS
+#  include <libintl.h>
+#  define _(msgid)   gettext (msgid)
+# else
+#  define _(msgid)   (msgid)
+# endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   ios_base::failure::failure(const string& __str) throw()
   : _M_msg(__str) { }
 
@@ -54,6 +56,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   const char*
   ios_base::failure::what() const throw()
   { return _M_msg.c_str(); }
+#endif
 
 #if _GLIBCXX_USE_DUAL_ABI
   // When the dual ABI is enabled __throw_ios_failure() is defined in
@@ -82,7 +85,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   }
 #endif // __cpp_rtti
 
-#else // ! _GLIBCXX_USE_DUAL_ABI
+#elif ! _GLIBCXX_USE_CXX11_ABI
 
   void
   __throw_ios_failure(const char* __s __attribute__((unused)))
@@ -92,7 +95,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   __throw_ios_failure(const char* str, int)
   { __throw_ios_failure(str); }
 
-#endif // _GLIBCXX_USE_DUAL_ABI
+#endif // ! _GLIBCXX_USE_CXX11_ABI
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+
+#endif // ! _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
diff --git a/libstdc++-v3/src/c++98/istream-string.cc b/libstdc++-v3/src/c++98/istream-string.cc
index 4859987fcc2..b64347f796e 100644
--- a/libstdc++-v3/src/c++98/istream-string.cc
+++ b/libstdc++-v3/src/c++98/istream-string.cc
@@ -31,6 +31,16 @@
 // by another file which defines _GLIBCXX_USE_CXX11_ABI=0.
 # define _GLIBCXX_USE_CXX11_ABI 1
 #endif
+
+#if _GLIBCXX_USE_CXX11_ABI
+# define _GLIBCXX_BUILD_CXX11_ABI 1
+#else
+# define _GLIBCXX_BUILD_CXX11_ABI 0
+#endif
+
+#include <bits/c++config.h>
+
+#if _GLIBCXX_BUILD_CXX11_ABI == _GLIBCXX_USE_CXX11_ABI
 #include <istream>
 #include <string>
 
@@ -289,3 +299,4 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
+#endif // _GLIBCXX_BUILD_CXX11_ABI == _GLIBCXX_USE_CXX11_ABI
diff --git a/libstdc++-v3/src/c++98/locale_facets.cc b/libstdc++-v3/src/c++98/locale_facets.cc
index c0bb7fd181d..7a929d51be4 100644
--- a/libstdc++-v3/src/c++98/locale_facets.cc
+++ b/libstdc++-v3/src/c++98/locale_facets.cc
@@ -125,6 +125,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     return __test;
   }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   bool
   __verify_grouping(const char* __grouping, size_t __grouping_size,
 		    const string& __grouping_tmp) throw()
@@ -133,6 +134,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                   __grouping_tmp.c_str(),
                                   __grouping_tmp.size());
   }
+#endif
 
   namespace
   {
diff --git a/libstdc++-v3/src/c++98/stdexcept.cc b/libstdc++-v3/src/c++98/stdexcept.cc
index e8c91f5c1cd..e82554e0aec 100644
--- a/libstdc++-v3/src/c++98/stdexcept.cc
+++ b/libstdc++-v3/src/c++98/stdexcept.cc
@@ -35,8 +35,10 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   logic_error::logic_error(const string& __arg)
   : exception(), _M_msg(__arg) { }
+#endif
 
   logic_error::~logic_error() _GLIBCXX_USE_NOEXCEPT { }
 
@@ -44,28 +46,38 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   logic_error::what() const _GLIBCXX_USE_NOEXCEPT
   { return _M_msg.c_str(); }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   domain_error::domain_error(const string& __arg)
   : logic_error(__arg) { }
+#endif
 
   domain_error::~domain_error() _GLIBCXX_USE_NOEXCEPT { }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   invalid_argument::invalid_argument(const string& __arg)
   : logic_error(__arg) { }
+#endif
 
   invalid_argument::~invalid_argument() _GLIBCXX_USE_NOEXCEPT { }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   length_error::length_error(const string& __arg)
   : logic_error(__arg) { }
+#endif
 
   length_error::~length_error() _GLIBCXX_USE_NOEXCEPT { }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   out_of_range::out_of_range(const string& __arg)
   : logic_error(__arg) { }
+#endif
 
   out_of_range::~out_of_range() _GLIBCXX_USE_NOEXCEPT { }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   runtime_error::runtime_error(const string& __arg)
   : exception(), _M_msg(__arg) { }
+#endif
 
   runtime_error::~runtime_error() _GLIBCXX_USE_NOEXCEPT { }
 
@@ -73,18 +85,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   runtime_error::what() const _GLIBCXX_USE_NOEXCEPT
   { return _M_msg.c_str(); }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   range_error::range_error(const string& __arg)
   : runtime_error(__arg) { }
+#endif
 
   range_error::~range_error() _GLIBCXX_USE_NOEXCEPT { }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   overflow_error::overflow_error(const string& __arg)
   : runtime_error(__arg) { }
+#endif
 
   overflow_error::~overflow_error() _GLIBCXX_USE_NOEXCEPT { }
 
+#if ! _GLIBCXX_USE_CXX11_ABI
   underflow_error::underflow_error(const string& __arg)
   : runtime_error(__arg) { }
+#endif
 
   underflow_error::~underflow_error() _GLIBCXX_USE_NOEXCEPT { }