diff --git a/libcxx/include/__split_buffer b/libcxx/include/__split_buffer
index 718fd88716cb..ea9d3d0463ef 100644
--- a/libcxx/include/__split_buffer
+++ b/libcxx/include/__split_buffer
@@ -98,11 +98,7 @@ public:
     _LIBCPP_INLINE_VISIBILITY void pop_back() {__destruct_at_end(__end_-1);}
 
     void __construct_at_end(size_type __n);
-        void __construct_at_end(size_type __n, false_type);
-        void __construct_at_end(size_type __n, true_type);
     void __construct_at_end(size_type __n, const_reference __x);
-        void __construct_at_end(size_type __n, const_reference __x, false_type);
-        void __construct_at_end(size_type __n, const_reference __x, true_type);
     template <class _InputIter>
         typename enable_if
         <
@@ -192,16 +188,8 @@ __split_buffer<_Tp, _Allocator>::__invariants() const
 //  Precondition:  size() + __n <= capacity()
 //  Postcondition:  size() == size() + __n
 template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
 void
 __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n)
-{
-    __construct_at_end(__n, __is_zero_default_constructible<value_type>());
-}
-
-template <class _Tp, class _Allocator>
-void
-__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, false_type)
 {
     __alloc_rr& __a = this->__alloc();
     do
@@ -212,15 +200,6 @@ __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, false_type)
     } while (__n > 0);
 }
 
-template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
-void
-__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, true_type)
-{
-    _STD::memset(this->__end_, 0, __n*sizeof(value_type));
-    this->__end_ += __n;
-}
-
 //  Copy constructs __n objects starting at __end_ from __x
 //  throws if construction throws
 //  Precondition:  __n > 0
@@ -228,17 +207,8 @@ __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, true_type)
 //  Postcondition:  size() == old size() + __n
 //  Postcondition:  [i] == __x for all i in [size() - __n, __n)
 template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
 void
 __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
-{
-    __construct_at_end(__n, __x, integral_constant<bool, is_trivially_copy_constructible<value_type>::value &&
-                                                         is_trivially_copy_assignable<value_type>::value>());
-}
-
-template <class _Tp, class _Allocator>
-void
-__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x, false_type)
 {
     __alloc_rr& __a = this->__alloc();
     do
@@ -249,15 +219,6 @@ __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_referen
     } while (__n > 0);
 }
 
-template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
-void
-__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x, true_type)
-{
-    _STD::fill_n(this->__end_, __n, __x);
-    this->__end_ += __n;
-}
-
 template <class _Tp, class _Allocator>
 template <class _InputIter>
 typename enable_if
diff --git a/libcxx/include/string b/libcxx/include/string
index 92f0ed19f777..469e3dd507ba 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -3641,10 +3641,6 @@ swap(basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Tra
     __lhs.swap(__rhs);
 }
 
-template<class _CharT, class _Traits, class _Allocator>
-struct __is_zero_default_constructible<basic_string<_CharT, _Traits, _Allocator> >
-    : public integral_constant<bool, __is_zero_default_constructible<_Allocator>::value> {};
-
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 
 typedef basic_string<char16_t> u16string;
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index db1cdb7a4b8e..50e357c0660a 100644
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -2302,9 +2302,6 @@ template <class _Tp> struct _LIBCPP_VISIBLE is_pod
 
 #endif  // _LIBCPP_HAS_TYPE_TRAITS
 
-template <class _Tp> struct __is_zero_default_constructible
-    : public integral_constant<bool, is_scalar<_Tp>::value || is_empty<_Tp>::value> {};
-
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 void
diff --git a/libcxx/include/vector b/libcxx/include/vector
index 9b9f2e815edb..7c0fc7052597 100644
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -624,14 +624,8 @@ private:
     void allocate(size_type __n);
     void deallocate();
     _LIBCPP_INLINE_VISIBILITY size_type __recommend(size_type __new_size) const;
-    _LIBCPP_INLINE_VISIBILITY void __construct_at_end(size_type __n);
-        void __construct_at_end(size_type __n, false_type);
-    _LIBCPP_INLINE_VISIBILITY void __construct_at_end(size_type __n, true_type);
-    _LIBCPP_INLINE_VISIBILITY
+    void __construct_at_end(size_type __n);
     void __construct_at_end(size_type __n, const_reference __x);
-    void __construct_at_end(size_type __n, const_reference __x, false_type);
-    _LIBCPP_INLINE_VISIBILITY
-        void __construct_at_end(size_type __n, const_reference __x, true_type);
     template <class _ForwardIterator>
         typename enable_if
         <
@@ -741,16 +735,8 @@ vector<_Tp, _Allocator>::__recommend(size_type __new_size) const
 //  Precondition:  size() + __n <= capacity()
 //  Postcondition:  size() == size() + __n
 template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
 void
 vector<_Tp, _Allocator>::__construct_at_end(size_type __n)
-{
-    __construct_at_end(__n, __is_zero_default_constructible<value_type>());
-}
-
-template <class _Tp, class _Allocator>
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, false_type)
 {
     allocator_type& __a = this->__alloc();
     do
@@ -761,15 +747,6 @@ vector<_Tp, _Allocator>::__construct_at_end(size_type __n, false_type)
     } while (__n > 0);
 }
 
-template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, true_type)
-{
-    _STD::memset(this->__end_, 0, __n*sizeof(value_type));
-    this->__end_ += __n;
-}
-
 //  Copy constructs __n objects starting at __end_ from __x
 //  throws if construction throws
 //  Precondition:  __n > 0
@@ -780,14 +757,6 @@ template <class _Tp, class _Allocator>
 _LIBCPP_INLINE_VISIBILITY inline
 void
 vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
-{
-    __construct_at_end(__n, __x, integral_constant<bool, is_trivially_copy_constructible<value_type>::value &&
-                                                         is_trivially_copy_assignable<value_type>::value>());
-}
-
-template <class _Tp, class _Allocator>
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x, false_type)
 {
     allocator_type& __a = this->__alloc();
     do
@@ -798,15 +767,6 @@ vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x,
     } while (__n > 0);
 }
 
-template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x, true_type)
-{
-    _STD::fill_n(this->__end_, __n, __x);
-    this->__end_ += __n;
-}
-
 template <class _Tp, class _Allocator>
 template <class _ForwardIterator>
 typename enable_if
@@ -2764,10 +2724,6 @@ struct _LIBCPP_VISIBLE hash<vector<bool, _Allocator> >
         {return __vec.__hash_code();}
 };
 
-template <class _Tp, class _Allocator>
-struct __is_zero_default_constructible<vector<_Tp, _Allocator> >
-    : public integral_constant<bool, __is_zero_default_constructible<_Allocator>::value> {};
-
 template <class _Tp, class _Allocator>
 _LIBCPP_INLINE_VISIBILITY inline
 bool