Index: include/array
===================================================================
--- include/array
+++ include/array
@@ -37,20 +37,20 @@
     void swap(array& a) noexcept(is_nothrow_swappable_v<T>);
 
     // iterators:
-    iterator begin() noexcept;
-    const_iterator begin() const noexcept;
-    iterator end() noexcept;
-    const_iterator end() const noexcept;
+    iterator begin() noexcept; // constexpr in C++17
+    const_iterator begin() const noexcept; // constexpr in C++17
+    iterator end() noexcept; // constexpr in C++17
+    const_iterator end() const noexcept; // constexpr in C++17
 
-    reverse_iterator rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-    reverse_iterator rend() noexcept;
-    const_reverse_iterator rend() const noexcept;
+    reverse_iterator rbegin() noexcept; // constexpr in C++17
+    const_reverse_iterator rbegin() const noexcept; // constexpr in C++17
+    reverse_iterator rend() noexcept; // constexpr in C++17
+    const_reverse_iterator rend() const noexcept; // constexpr in C++17
 
-    const_iterator cbegin() const noexcept;
-    const_iterator cend() const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend() const noexcept;
+    const_iterator cbegin() const noexcept; // constexpr in C++17
+    const_iterator cend() const noexcept; // constexpr in C++17
+    const_reverse_iterator crbegin() const noexcept; // constexpr in C++17
+    const_reverse_iterator crend() const noexcept; // constexpr in C++17
 
     // capacity:
     constexpr size_type size() const noexcept;
@@ -58,18 +58,18 @@
     constexpr bool empty() const noexcept;
 
     // element access:
-    reference operator[](size_type n);
+    reference operator[](size_type n); // constexpr in C++17
     const_reference operator[](size_type n) const; // constexpr in C++14
     const_reference at(size_type n) const; // constexpr in C++14
-    reference at(size_type n);
+    reference at(size_type n); // constexpr in C++17
 
-    reference front();
+    reference front(); // constexpr in C++17
     const_reference front() const; // constexpr in C++14
-    reference back();
+    reference back(); // constexpr in C++17
     const_reference back() const; // constexpr in C++14
 
-    T* data() noexcept;
-    const T* data() const noexcept;
+    T* data() noexcept; // constexpr in C++17
+    const T* data() const noexcept; // constexpr in C++17
 };
 
 template <class T, size_t N>
@@ -153,22 +153,22 @@
 
     // iterators:
     _LIBCPP_INLINE_VISIBILITY
-    iterator begin() _NOEXCEPT {return iterator(__elems_);}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 iterator begin() _NOEXCEPT {return iterator(__elems_);}
     _LIBCPP_INLINE_VISIBILITY
-    const_iterator begin() const _NOEXCEPT {return const_iterator(__elems_);}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 const_iterator begin() const _NOEXCEPT {return const_iterator(__elems_);}
     _LIBCPP_INLINE_VISIBILITY
-    iterator end() _NOEXCEPT {return iterator(__elems_ + _Size);}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 iterator end() _NOEXCEPT {return iterator(__elems_ + _Size);}
     _LIBCPP_INLINE_VISIBILITY
-    const_iterator end() const _NOEXCEPT {return const_iterator(__elems_ + _Size);}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 const_iterator end() const _NOEXCEPT {return const_iterator(__elems_ + _Size);}
 
     _LIBCPP_INLINE_VISIBILITY
-    reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
     _LIBCPP_INLINE_VISIBILITY
-    const_reverse_iterator rbegin() const _NOEXCEPT {return const_reverse_iterator(end());}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 const_reverse_iterator rbegin() const _NOEXCEPT {return const_reverse_iterator(end());}
     _LIBCPP_INLINE_VISIBILITY
-    reverse_iterator rend() _NOEXCEPT {return reverse_iterator(begin());}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 reverse_iterator rend() _NOEXCEPT {return reverse_iterator(begin());}
     _LIBCPP_INLINE_VISIBILITY
-    const_reverse_iterator rend() const _NOEXCEPT {return const_reverse_iterator(begin());}
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 const_reverse_iterator rend() const _NOEXCEPT {return const_reverse_iterator(begin());}
 
     _LIBCPP_INLINE_VISIBILITY
     const_iterator cbegin() const _NOEXCEPT {return begin();}
@@ -188,23 +188,24 @@
     _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return _Size == 0;}
 
     // element access:
-    _LIBCPP_INLINE_VISIBILITY reference operator[](size_type __n)             {return __elems_[__n];}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference operator[](size_type __n)             {return __elems_[__n];}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference operator[](size_type __n) const {return __elems_[__n];}
-    reference at(size_type __n);
+    _LIBCPP_CONSTEXPR_AFTER_CXX14 reference at(size_type __n);
     _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference at(size_type __n) const;
 
-    _LIBCPP_INLINE_VISIBILITY reference front()             {return __elems_[0];}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference front()             {return __elems_[0];}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference front() const {return __elems_[0];}
-    _LIBCPP_INLINE_VISIBILITY reference back()              {return __elems_[_Size > 0 ? _Size-1 : 0];}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference back()              {return __elems_[_Size > 0 ? _Size-1 : 0];}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference back() const  {return __elems_[_Size > 0 ? _Size-1 : 0];}
 
     _LIBCPP_INLINE_VISIBILITY
-    value_type* data() _NOEXCEPT {return __elems_;}
+    value_type* _LIBCPP_CONSTEXPR_AFTER_CXX14 data() _NOEXCEPT {return __elems_;}
     _LIBCPP_INLINE_VISIBILITY
-    const value_type* data() const _NOEXCEPT {return __elems_;}
+    const value_type* _LIBCPP_CONSTEXPR_AFTER_CXX14 data() const _NOEXCEPT {return __elems_;}
 };
 
 template <class _Tp, size_t _Size>
+_LIBCPP_CONSTEXPR_AFTER_CXX14
 typename array<_Tp, _Size>::reference
 array<_Tp, _Size>::at(size_type __n)
 {
Index: include/iterator
===================================================================
--- include/iterator
+++ include/iterator
@@ -372,25 +372,25 @@
     bool failed() const noexcept;
 };
 
-template <class C> auto begin(C& c) -> decltype(c.begin());
-template <class C> auto begin(const C& c) -> decltype(c.begin());
-template <class C> auto end(C& c) -> decltype(c.end());
-template <class C> auto end(const C& c) -> decltype(c.end());
-template <class T, size_t N> T* begin(T (&array)[N]);
-template <class T, size_t N> T* end(T (&array)[N]);
-
-template <class C> auto cbegin(const C& c) -> decltype(std::begin(c));        // C++14
-template <class C> auto cend(const C& c) -> decltype(std::end(c));            // C++14
-template <class C> auto rbegin(C& c) -> decltype(c.rbegin());                 // C++14
-template <class C> auto rbegin(const C& c) -> decltype(c.rbegin());           // C++14
-template <class C> auto rend(C& c) -> decltype(c.rend());                     // C++14
-template <class C> auto rend(const C& c) -> decltype(c.rend());               // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto begin(C& c) -> decltype(c.begin());
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto begin(const C& c) -> decltype(c.begin());
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto end(C& c) -> decltype(c.end());
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto end(const C& c) -> decltype(c.end());
+template <class T, size_t N> _LIBCPP_CONSTEXPR_AFTER_CXX14 T* begin(T (&array)[N]);
+template <class T, size_t N> _LIBCPP_CONSTEXPR_AFTER_CXX14 T* end(T (&array)[N]);
+
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto cbegin(const C& c) -> decltype(std::begin(c));        // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto cend(const C& c) -> decltype(std::end(c));            // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto rbegin(C& c) -> decltype(c.rbegin());                 // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto rbegin(const C& c) -> decltype(c.rbegin());           // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto rend(C& c) -> decltype(c.rend());                     // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto rend(const C& c) -> decltype(c.rend());               // C++14
 template <class E> reverse_iterator<const E*> rbegin(initializer_list<E> il); // C++14
 template <class E> reverse_iterator<const E*> rend(initializer_list<E> il);   // C++14
-template <class T, size_t N> reverse_iterator<T*> rbegin(T (&array)[N]);      // C++14
-template <class T, size_t N> reverse_iterator<T*> rend(T (&array)[N]);        // C++14
-template <class C> auto crbegin(const C& c) -> decltype(std::rbegin(c));      // C++14
-template <class C> auto crend(const C& c) -> decltype(std::rend(c));          // C++14
+template <class T, size_t N> _LIBCPP_CONSTEXPR_AFTER_CXX14 reverse_iterator<T*> rbegin(T (&array)[N]);      // C++14
+template <class T, size_t N> _LIBCPP_CONSTEXPR_AFTER_CXX14 reverse_iterator<T*> rend(T (&array)[N]);        // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto crbegin(const C& c) -> decltype(std::rbegin(c));      // C++14
+template <class C> _LIBCPP_CONSTEXPR_AFTER_CXX14 auto crend(const C& c) -> decltype(std::rend(c));          // C++14
 
 // 24.8, container access:
 template <class C> constexpr auto size(const C& c) -> decltype(c.size());         // C++17
@@ -1569,7 +1569,7 @@
 #if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_TRAILING_RETURN)
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto
 begin(_Cp& __c) -> decltype(__c.begin())
 {
@@ -1577,7 +1577,7 @@
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto
 begin(const _Cp& __c) -> decltype(__c.begin())
 {
@@ -1585,7 +1585,7 @@
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto
 end(_Cp& __c) -> decltype(__c.end())
 {
@@ -1593,7 +1593,7 @@
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto
 end(const _Cp& __c) -> decltype(__c.end())
 {
@@ -1603,14 +1603,14 @@
 #if _LIBCPP_STD_VER > 11
 
 template <class _Tp, size_t _Np>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 reverse_iterator<_Tp*> rbegin(_Tp (&__array)[_Np])
 {
     return reverse_iterator<_Tp*>(__array + _Np);
 }
 
 template <class _Tp, size_t _Np>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 reverse_iterator<_Tp*> rend(_Tp (&__array)[_Np])
 {
     return reverse_iterator<_Tp*>(__array);
@@ -1645,42 +1645,42 @@
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto rbegin(_Cp& __c) -> decltype(__c.rbegin())
 {
     return __c.rbegin();
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto rbegin(const _Cp& __c) -> decltype(__c.rbegin())
 {
     return __c.rbegin();
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto rend(_Cp& __c) -> decltype(__c.rend())
 {
     return __c.rend();
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto rend(const _Cp& __c) -> decltype(__c.rend())
 {
     return __c.rend();
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto crbegin(const _Cp& __c) -> decltype(rbegin(__c))
 {
     return rbegin(__c);
 }
 
 template <class _Cp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 auto crend(const _Cp& __c) -> decltype(rend(__c))
 {
     return rend(__c);