diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 1e5b30c8aac..cadee8312b4 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,28 @@
 2015-05-27  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/stl_tree.h (_Rb_tree::_M_end()): Return _Base_ptr
+	instead of downcasting.
+	(_Rb_tree::_M_copy): Change second parameter to _Base_ptr.
+	(_Rb_tree::_M_lower_bound, _Rb_tree:_M_upper_bound): Likewise.
+	(_Rb_tree::_S_iter): Remove.
+	(_Rb_tree::_S_lower_bound_tr, _Rb_tree::_S_upper_bound_tr): Remove.
+	(_Rb_tree::_M_find_tr(const _Kt&) const): Call _M_lower_bound_tr
+	instead of _S_lower_bound_tr
+	(_Rb_tree::_M_find_tr(const _Kt&)): Call const overload.
+	(_Rb_tree::_M_lower_bound_tr(const _Kt&) const): Do the search here
+	instead of calling _S_lower_bound_tr.
+	(_Rb_tree::_M_lower_bound_tr(const _Kt&)): Call const overload.
+	(_Rb_tree::_M_upper_bound_tr(const _Kt&) const): Do the search here
+	instead of calling _S_upper_bound_tr.
+	(_Rb_tree::_M_upper_bound_tr(const _Kt&)): Call const overload.
+	(_Rb_tree::_M_equal_range_tr(const _Kt&)): Likewise.
+	(_Rb_tree::equal_range): Use _Base_ptr for end pointer.
+	(_Rb_tree::_M_get_insert_unique_pos): Likewise.
+	(_Rb_tree::_M_get_insert_equal_pos): Likewise.
+	(_Rb_tree::_M_insert_equal_lower_node): Likewise.
+	(_Rb_tree::_M_insert_unique, _Rb_tree::_M_emplace_unique,
+	_Rb_tree::_M_emplace_hint_unique): Remove static_cast.
+
 	PR libstdc++/66017
 	* include/bits/stl_tree.h (_Rb_tree_node): Use __aligned_membuf.
 	(_Rb_tree_iterator, _Rb_tree_const_iterator): Support construction
diff --git a/libstdc++-v3/include/bits/stl_tree.h b/libstdc++-v3/include/bits/stl_tree.h
index d39042f1aaf..240f5228530 100644
--- a/libstdc++-v3/include/bits/stl_tree.h
+++ b/libstdc++-v3/include/bits/stl_tree.h
@@ -658,13 +658,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  (this->_M_impl._M_header._M_parent);
       }
 
-      _Link_type
+      _Base_ptr
       _M_end() _GLIBCXX_NOEXCEPT
-      { return reinterpret_cast<_Link_type>(&this->_M_impl._M_header); }
+      { return &this->_M_impl._M_header; }
 
-      _Const_Link_type
+      _Const_Base_ptr
       _M_end() const _GLIBCXX_NOEXCEPT
-      { return reinterpret_cast<_Const_Link_type>(&this->_M_impl._M_header); }
+      { return &this->_M_impl._M_header; }
 
       static const_reference
       _S_value(_Const_Link_type __x)
@@ -774,10 +774,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       template<typename _NodeGen>
 	_Link_type
-	_M_copy(_Const_Link_type __x, _Link_type __p, _NodeGen&);
+	_M_copy(_Const_Link_type __x, _Base_ptr __p, _NodeGen&);
 
       _Link_type
-      _M_copy(_Const_Link_type __x, _Link_type __p)
+      _M_copy(_Const_Link_type __x, _Base_ptr __p)
       {
 	_Alloc_node __an(*this);
 	return _M_copy(__x, __p, __an);
@@ -787,19 +787,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _M_erase(_Link_type __x);
 
       iterator
-      _M_lower_bound(_Link_type __x, _Link_type __y,
+      _M_lower_bound(_Link_type __x, _Base_ptr __y,
 		     const _Key& __k);
 
       const_iterator
-      _M_lower_bound(_Const_Link_type __x, _Const_Link_type __y,
+      _M_lower_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 		     const _Key& __k) const;
 
       iterator
-      _M_upper_bound(_Link_type __x, _Link_type __y,
+      _M_upper_bound(_Link_type __x, _Base_ptr __y,
 		     const _Key& __k);
 
       const_iterator
-      _M_upper_bound(_Const_Link_type __x, _Const_Link_type __y,
+      _M_upper_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 		     const _Key& __k) const;
 
     public:
@@ -1117,43 +1117,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	__is_transparent<_Cmp, _Kt, __void_t<typename _Cmp::is_transparent>>
 	{ typedef void type; };
 
-      static auto _S_iter(_Link_type __x) { return iterator(__x); }
-
-      static auto _S_iter(_Const_Link_type __x) { return const_iterator(__x); }
-
-      template<typename _Cmp, typename _Link, typename _Kt>
-	static auto
-	_S_lower_bound_tr(_Cmp& __cmp, _Link __x, _Link __y, const _Kt& __k)
-	{
-	  while (__x != 0)
-	    if (!__cmp(_S_key(__x), __k))
-	      __y = __x, __x = _S_left(__x);
-	    else
-	      __x = _S_right(__x);
-	  return _S_iter(__y);
-	}
-
-      template<typename _Cmp, typename _Link, typename _Kt>
-	static auto
-	_S_upper_bound_tr(_Cmp& __cmp, _Link __x, _Link __y, const _Kt& __k)
-	{
-	  while (__x != 0)
-	    if (__cmp(__k, _S_key(__x)))
-	      __y = __x, __x = _S_left(__x);
-	    else
-	      __x = _S_right(__x);
-	  return _S_iter(__y);
-	}
-
       template<typename _Kt,
 	       typename _Req = typename __is_transparent<_Compare, _Kt>::type>
 	iterator
 	_M_find_tr(const _Kt& __k)
 	{
-	  auto& __cmp = _M_impl._M_key_compare;
-	  auto __j = _S_lower_bound_tr(__cmp, _M_begin(), _M_end(), __k);
-	  return (__j == end() || __cmp(__k, _S_key(__j._M_node)))
-	    ? end() : __j;
+	  const _Rb_tree* __const_this = this;
+	  return __const_this->_M_find_tr(__k)._M_const_cast();
 	}
 
       template<typename _Kt,
@@ -1161,10 +1131,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	const_iterator
 	_M_find_tr(const _Kt& __k) const
 	{
-	  auto& __cmp = _M_impl._M_key_compare;
-	  auto __j = _S_lower_bound_tr(__cmp, _M_begin(), _M_end(), __k);
-	  return (__j == end() || __cmp(__k, _S_key(__j._M_node)))
-	    ? end() : __j;
+	  auto __j = _M_lower_bound_tr(__k);
+	  if (__j != end() && _M_impl._M_key_compare(__k, _S_key(__j._M_node)))
+	    __j = end();
+	  return __j;
 	}
 
       template<typename _Kt,
@@ -1181,8 +1151,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	iterator
 	_M_lower_bound_tr(const _Kt& __k)
 	{
-	  auto& __cmp = _M_impl._M_key_compare;
-	  return _S_lower_bound_tr(__cmp, _M_begin(), _M_end(), __k);
+	  const _Rb_tree* __const_this = this;
+	  return __const_this->_M_lower_bound_tr(__k)._M_const_cast();
 	}
 
       template<typename _Kt,
@@ -1190,8 +1160,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	const_iterator
 	_M_lower_bound_tr(const _Kt& __k) const
 	{
-	  auto& __cmp = _M_impl._M_key_compare;
-	  return _S_lower_bound_tr(__cmp, _M_begin(), _M_end(), __k);
+	  auto __x = _M_begin();
+	  auto __y = _M_end();
+	  while (__x != 0)
+	    if (!_M_impl._M_key_compare(_S_key(__x), __k))
+	      {
+		__y = __x;
+		__x = _S_left(__x);
+	      }
+	    else
+	      __x = _S_right(__x);
+	  return const_iterator(__y);
 	}
 
       template<typename _Kt,
@@ -1199,8 +1178,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	iterator
 	_M_upper_bound_tr(const _Kt& __k)
 	{
-	  auto& __cmp = _M_impl._M_key_compare;
-	  return _S_upper_bound_tr(__cmp, _M_begin(), _M_end(), __k);
+	  const _Rb_tree* __const_this = this;
+	  return __const_this->_M_upper_bound_tr(__k)._M_const_cast();
 	}
 
       template<typename _Kt,
@@ -1208,8 +1187,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	const_iterator
 	_M_upper_bound_tr(const _Kt& __k) const
 	{
-	  auto& __cmp = _M_impl._M_key_compare;
-	  return _S_upper_bound_tr(__cmp, _M_begin(), _M_end(), __k);
+	  auto __x = _M_begin();
+	  auto __y = _M_end();
+	  while (__x != 0)
+	    if (_M_impl._M_key_compare(__k, _S_key(__x)))
+	      {
+		__y = __x;
+		__x = _S_left(__x);
+	      }
+	    else
+	      __x = _S_right(__x);
+	  return const_iterator(__y);
 	}
 
       template<typename _Kt,
@@ -1217,12 +1205,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	pair<iterator, iterator>
 	_M_equal_range_tr(const _Kt& __k)
 	{
-	  auto __low = _M_lower_bound_tr(__k);
-	  auto __high = __low;
-	  auto& __cmp = _M_impl._M_key_compare;
-	  while (__high != end() && !__cmp(__k, _S_key(__high._M_node)))
-	    ++__high;
-	  return { __low, __high };
+	  const _Rb_tree* __const_this = this;
+	  auto __ret = __const_this->_M_equal_range_tr(__k);
+	  return { __ret.first._M_const_cast(), __ret.second._M_const_cast() };
 	}
 
       template<typename _Kt,
@@ -1553,7 +1538,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #endif
     {
       _Link_type __x = _M_begin();
-      _Link_type __y = _M_end();
+      _Base_ptr __y = _M_end();
       while (__x != 0)
 	{
 	  __y = __x;
@@ -1568,7 +1553,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     template<typename _NodeGen>
       typename _Rb_tree<_Key, _Val, _KoV, _Compare, _Alloc>::_Link_type
       _Rb_tree<_Key, _Val, _KoV, _Compare, _Alloc>::
-      _M_copy(_Const_Link_type __x, _Link_type __p, _NodeGen& __node_gen)
+      _M_copy(_Const_Link_type __x, _Base_ptr __p, _NodeGen& __node_gen)
       {
 	// Structural copy. __x and __p must be non-null.
 	_Link_type __top = _M_clone_node(__x, __node_gen);
@@ -1621,7 +1606,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     typename _Rb_tree<_Key, _Val, _KeyOfValue,
 		      _Compare, _Alloc>::iterator
     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
-    _M_lower_bound(_Link_type __x, _Link_type __y,
+    _M_lower_bound(_Link_type __x, _Base_ptr __y,
 		   const _Key& __k)
     {
       while (__x != 0)
@@ -1637,7 +1622,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     typename _Rb_tree<_Key, _Val, _KeyOfValue,
 		      _Compare, _Alloc>::const_iterator
     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
-    _M_lower_bound(_Const_Link_type __x, _Const_Link_type __y,
+    _M_lower_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 		   const _Key& __k) const
     {
       while (__x != 0)
@@ -1653,7 +1638,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     typename _Rb_tree<_Key, _Val, _KeyOfValue,
 		      _Compare, _Alloc>::iterator
     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
-    _M_upper_bound(_Link_type __x, _Link_type __y,
+    _M_upper_bound(_Link_type __x, _Base_ptr __y,
 		   const _Key& __k)
     {
       while (__x != 0)
@@ -1669,7 +1654,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     typename _Rb_tree<_Key, _Val, _KeyOfValue,
 		      _Compare, _Alloc>::const_iterator
     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
-    _M_upper_bound(_Const_Link_type __x, _Const_Link_type __y,
+    _M_upper_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 		   const _Key& __k) const
     {
       while (__x != 0)
@@ -1690,7 +1675,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     equal_range(const _Key& __k)
     {
       _Link_type __x = _M_begin();
-      _Link_type __y = _M_end();
+      _Base_ptr __y = _M_end();
       while (__x != 0)
 	{
 	  if (_M_impl._M_key_compare(_S_key(__x), __k))
@@ -1699,7 +1684,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    __y = __x, __x = _S_left(__x);
 	  else
 	    {
-	      _Link_type __xu(__x), __yu(__y);
+	      _Link_type __xu(__x);
+	      _Base_ptr __yu(__y);
 	      __y = __x, __x = _S_left(__x);
 	      __xu = _S_right(__xu);
 	      return pair<iterator,
@@ -1721,7 +1707,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     equal_range(const _Key& __k) const
     {
       _Const_Link_type __x = _M_begin();
-      _Const_Link_type __y = _M_end();
+      _Const_Base_ptr __y = _M_end();
       while (__x != 0)
 	{
 	  if (_M_impl._M_key_compare(_S_key(__x), __k))
@@ -1730,7 +1716,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    __y = __x, __x = _S_left(__x);
 	  else
 	    {
-	      _Const_Link_type __xu(__x), __yu(__y);
+	      _Const_Link_type __xu(__x);
+	      _Const_Base_ptr __yu(__y);
 	      __y = __x, __x = _S_left(__x);
 	      __xu = _S_right(__xu);
 	      return pair<const_iterator,
@@ -1802,7 +1789,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       typedef pair<_Base_ptr, _Base_ptr> _Res;
       _Link_type __x = _M_begin();
-      _Link_type __y = _M_end();
+      _Base_ptr __y = _M_end();
       bool __comp = true;
       while (__x != 0)
 	{
@@ -1834,7 +1821,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       typedef pair<_Base_ptr, _Base_ptr> _Res;
       _Link_type __x = _M_begin();
-      _Link_type __y = _M_end();
+      _Base_ptr __y = _M_end();
       while (__x != 0)
 	{
 	  __y = __x;
@@ -1870,7 +1857,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		      true);
 	}
 
-      return _Res(iterator(static_cast<_Link_type>(__res.first)), false);
+      return _Res(iterator(__res.first), false);
     }
 
   template<typename _Key, typename _Val, typename _KeyOfValue,
@@ -1976,7 +1963,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	return _M_insert_(__res.first, __res.second,
 			  _GLIBCXX_FORWARD(_Arg, __v),
 			  __node_gen);
-      return iterator(static_cast<_Link_type>(__res.first));
+      return iterator(__res.first);
     }
 
   template<typename _Key, typename _Val, typename _KeyOfValue,
@@ -2102,7 +2089,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_insert_equal_lower_node(_Link_type __z)
     {
       _Link_type __x = _M_begin();
-      _Link_type __y = _M_end();
+      _Base_ptr __y = _M_end();
       while (__x != 0)
 	{
 	  __y = __x;
@@ -2130,7 +2117,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      return _Res(_M_insert_node(__res.first, __res.second, __z), true);
 	
 	    _M_drop_node(__z);
-	    return _Res(iterator(static_cast<_Link_type>(__res.first)), false);
+	    return _Res(iterator(__res.first), false);
 	  }
 	__catch(...)
 	  {
@@ -2177,7 +2164,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      return _M_insert_node(__res.first, __res.second, __z);
 
 	    _M_drop_node(__z);
-	    return iterator(static_cast<_Link_type>(__res.first));
+	    return iterator(__res.first);
 	  }
 	__catch(...)
 	  {