diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -130,27 +130,34 @@
   __functional/unwrap_ref.h
   __functional/weak_result_type.h
   __hash_table
+  __iterator/access.h
   __iterator/advance.h
   __iterator/back_insert_iterator.h
   __iterator/concepts.h
+  __iterator/data.h
   __iterator/default_sentinel.h
+  __iterator/distance.h
+  __iterator/empty.h
+  __iterator/erase_if_container.h
   __iterator/front_insert_iterator.h
   __iterator/incrementable_traits.h
   __iterator/insert_iterator.h
-  __iterator/istream_iterator.h
   __iterator/istreambuf_iterator.h
+  __iterator/istream_iterator.h
+  __iterator/iterator.h
+  __iterator/iterator_traits.h
   __iterator/iter_move.h
   __iterator/iter_swap.h
-  __iterator/iterator_traits.h
-  __iterator/iterator.h
   __iterator/move_iterator.h
   __iterator/next.h
-  __iterator/ostream_iterator.h
   __iterator/ostreambuf_iterator.h
+  __iterator/ostream_iterator.h
   __iterator/prev.h
   __iterator/projected.h
   __iterator/readable_traits.h
+  __iterator/reverse_access.h
   __iterator/reverse_iterator.h
+  __iterator/size.h
   __iterator/wrap_iter.h
   __libcpp_version
   __locale
diff --git a/libcxx/include/__iterator/access.h b/libcxx/include/__iterator/access.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/access.h
@@ -0,0 +1,134 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_ACCESS_H
+#define _LIBCPP___ITERATOR_ACCESS_H
+
+#include <__config>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, size_t _Np>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_Tp*
+begin(_Tp (&__array)[_Np])
+{
+    return __array;
+}
+
+template <class _Tp, size_t _Np>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_Tp*
+end(_Tp (&__array)[_Np])
+{
+    return __array + _Np;
+}
+
+#if !defined(_LIBCPP_CXX03_LANG)
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto
+begin(_Cp& __c) -> decltype(__c.begin())
+{
+    return __c.begin();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto
+begin(const _Cp& __c) -> decltype(__c.begin())
+{
+    return __c.begin();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto
+end(_Cp& __c) -> decltype(__c.end())
+{
+    return __c.end();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto
+end(const _Cp& __c) -> decltype(__c.end())
+{
+    return __c.end();
+}
+
+#if _LIBCPP_STD_VER > 11
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+auto cbegin(const _Cp& __c) -> decltype(_VSTD::begin(__c))
+{
+    return _VSTD::begin(__c);
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+auto cend(const _Cp& __c) -> decltype(_VSTD::end(__c))
+{
+    return _VSTD::end(__c);
+}
+
+#endif
+
+
+#else  // defined(_LIBCPP_CXX03_LANG)
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY
+typename _Cp::iterator
+begin(_Cp& __c)
+{
+    return __c.begin();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY
+typename _Cp::const_iterator
+begin(const _Cp& __c)
+{
+    return __c.begin();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY
+typename _Cp::iterator
+end(_Cp& __c)
+{
+    return __c.end();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY
+typename _Cp::const_iterator
+end(const _Cp& __c)
+{
+    return __c.end();
+}
+
+#endif // !defined(_LIBCPP_CXX03_LANG)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_ACCESS_H
diff --git a/libcxx/include/__iterator/back_insert_iterator.h b/libcxx/include/__iterator/back_insert_iterator.h
--- a/libcxx/include/__iterator/back_insert_iterator.h
+++ b/libcxx/include/__iterator/back_insert_iterator.h
@@ -11,11 +11,11 @@
 #define _LIBCPP___ITERATOR_BACK_INSERT_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
+#include <__utility/move.h>
 #include <cstddef>
-#include <utility> // std::move
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/__iterator/data.h b/libcxx/include/__iterator/data.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/data.h
@@ -0,0 +1,56 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_DATA_H
+#define _LIBCPP___ITERATOR_DATA_H
+
+#include <__config>
+#include <cstddef>
+#include <initializer_list>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 14
+
+template <class _Cont> constexpr
+_LIBCPP_INLINE_VISIBILITY
+auto data(_Cont& __c)
+_NOEXCEPT_(noexcept(__c.data()))
+-> decltype        (__c.data())
+{ return            __c.data(); }
+
+template <class _Cont> constexpr
+_LIBCPP_INLINE_VISIBILITY
+auto data(const _Cont& __c)
+_NOEXCEPT_(noexcept(__c.data()))
+-> decltype        (__c.data())
+{ return            __c.data(); }
+
+template <class _Tp, size_t _Sz>
+_LIBCPP_INLINE_VISIBILITY
+constexpr _Tp* data(_Tp (&__array)[_Sz]) noexcept { return __array; }
+
+template <class _Ep>
+_LIBCPP_INLINE_VISIBILITY
+constexpr const _Ep* data(initializer_list<_Ep> __il) noexcept { return __il.begin(); }
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_DATA_H
diff --git a/libcxx/include/__iterator/distance.h b/libcxx/include/__iterator/distance.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/distance.h
@@ -0,0 +1,56 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_DISTANCE_H
+#define _LIBCPP___ITERATOR_DISTANCE_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIter>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+typename iterator_traits<_InputIter>::difference_type
+__distance(_InputIter __first, _InputIter __last, input_iterator_tag)
+{
+    typename iterator_traits<_InputIter>::difference_type __r(0);
+    for (; __first != __last; ++__first)
+        ++__r;
+    return __r;
+}
+
+template <class _RandIter>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+typename iterator_traits<_RandIter>::difference_type
+__distance(_RandIter __first, _RandIter __last, random_access_iterator_tag)
+{
+    return __last - __first;
+}
+
+template <class _InputIter>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+typename iterator_traits<_InputIter>::difference_type
+distance(_InputIter __first, _InputIter __last)
+{
+    return _VSTD::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_DISTANCE_H
diff --git a/libcxx/include/__iterator/empty.h b/libcxx/include/__iterator/empty.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/empty.h
@@ -0,0 +1,49 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_EMPTY_H
+#define _LIBCPP___ITERATOR_EMPTY_H
+
+#include <__config>
+#include <cstddef>
+#include <initializer_list>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 14
+
+template <class _Cont>
+_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
+constexpr auto empty(const _Cont& __c)
+_NOEXCEPT_(noexcept(__c.empty()))
+-> decltype        (__c.empty())
+{ return            __c.empty(); }
+
+template <class _Tp, size_t _Sz>
+_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
+constexpr bool empty(const _Tp (&)[_Sz]) noexcept { return false; }
+
+template <class _Ep>
+_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
+constexpr bool empty(initializer_list<_Ep> __il) noexcept { return __il.size() == 0; }
+
+#endif // _LIBCPP_STD_VER > 14
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_EMPTY_H
diff --git a/libcxx/include/__iterator/erase_if_container.h b/libcxx/include/__iterator/erase_if_container.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/erase_if_container.h
@@ -0,0 +1,44 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_ERASE_IF_CONTAINER_H
+#define _LIBCPP___ITERATOR_ERASE_IF_CONTAINER_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Container, class _Predicate>
+typename _Container::size_type
+__libcpp_erase_if_container(_Container& __c, _Predicate& __pred) {
+  typename _Container::size_type __old_size = __c.size();
+
+  const typename _Container::iterator __last = __c.end();
+  for (typename _Container::iterator __iter = __c.begin(); __iter != __last;) {
+    if (__pred(*__iter))
+      __iter = __c.erase(__iter);
+    else
+      ++__iter;
+  }
+
+  return __old_size - __c.size();
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_ERASE_IF_CONTAINER_H
diff --git a/libcxx/include/__iterator/front_insert_iterator.h b/libcxx/include/__iterator/front_insert_iterator.h
--- a/libcxx/include/__iterator/front_insert_iterator.h
+++ b/libcxx/include/__iterator/front_insert_iterator.h
@@ -11,11 +11,11 @@
 #define _LIBCPP___ITERATOR_FRONT_INSERT_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
+#include <__utility/move.h>
 #include <cstddef>
-#include <utility> // std::move
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/__iterator/insert_iterator.h b/libcxx/include/__iterator/insert_iterator.h
--- a/libcxx/include/__iterator/insert_iterator.h
+++ b/libcxx/include/__iterator/insert_iterator.h
@@ -11,11 +11,11 @@
 #define _LIBCPP___ITERATOR_INSERT_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
+#include <__utility/move.h>
 #include <cstddef>
-#include <utility> // std::move
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/__iterator/istream_iterator.h b/libcxx/include/__iterator/istream_iterator.h
--- a/libcxx/include/__iterator/istream_iterator.h
+++ b/libcxx/include/__iterator/istream_iterator.h
@@ -11,10 +11,9 @@
 #define _LIBCPP___ITERATOR_ISTREAM_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
-#include <cstddef>
 #include <iosfwd> // for forward declarations of char_traits and basic_istream
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__iterator/istreambuf_iterator.h b/libcxx/include/__iterator/istreambuf_iterator.h
--- a/libcxx/include/__iterator/istreambuf_iterator.h
+++ b/libcxx/include/__iterator/istreambuf_iterator.h
@@ -11,8 +11,8 @@
 #define _LIBCPP___ITERATOR_ISTREAMBUF_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <iosfwd> // for forward declaration of basic_streambuf
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__iterator/ostream_iterator.h b/libcxx/include/__iterator/ostream_iterator.h
--- a/libcxx/include/__iterator/ostream_iterator.h
+++ b/libcxx/include/__iterator/ostream_iterator.h
@@ -11,10 +11,9 @@
 #define _LIBCPP___ITERATOR_OSTREAM_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
-#include <cstddef>
 #include <iosfwd> // for forward declarations of char_traits and basic_ostream
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__iterator/ostreambuf_iterator.h b/libcxx/include/__iterator/ostreambuf_iterator.h
--- a/libcxx/include/__iterator/ostreambuf_iterator.h
+++ b/libcxx/include/__iterator/ostreambuf_iterator.h
@@ -11,8 +11,8 @@
 #define _LIBCPP___ITERATOR_OSTREAMBUF_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <iosfwd> // for forward declaration of basic_streambuf
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__iterator/reverse_access.h b/libcxx/include/__iterator/reverse_access.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/reverse_access.h
@@ -0,0 +1,109 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_REVERSE_ACCESS_H
+#define _LIBCPP___ITERATOR_REVERSE_ACCESS_H
+
+#include <__config>
+#include <__iterator/reverse_iterator.h>
+#include <cstddef>
+#include <initializer_list>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if !defined(_LIBCPP_CXX03_LANG)
+
+#if _LIBCPP_STD_VER > 11
+
+template <class _Tp, size_t _Np>
+_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>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+reverse_iterator<_Tp*> rend(_Tp (&__array)[_Np])
+{
+    return reverse_iterator<_Tp*>(__array);
+}
+
+template <class _Ep>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+reverse_iterator<const _Ep*> rbegin(initializer_list<_Ep> __il)
+{
+    return reverse_iterator<const _Ep*>(__il.end());
+}
+
+template <class _Ep>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+reverse_iterator<const _Ep*> rend(initializer_list<_Ep> __il)
+{
+    return reverse_iterator<const _Ep*>(__il.begin());
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto rbegin(_Cp& __c) -> decltype(__c.rbegin())
+{
+    return __c.rbegin();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto rbegin(const _Cp& __c) -> decltype(__c.rbegin())
+{
+    return __c.rbegin();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto rend(_Cp& __c) -> decltype(__c.rend())
+{
+    return __c.rend();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto rend(const _Cp& __c) -> decltype(__c.rend())
+{
+    return __c.rend();
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto crbegin(const _Cp& __c) -> decltype(_VSTD::rbegin(__c))
+{
+    return _VSTD::rbegin(__c);
+}
+
+template <class _Cp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+auto crend(const _Cp& __c) -> decltype(_VSTD::rend(__c))
+{
+    return _VSTD::rend(__c);
+}
+
+#endif
+
+#endif // !defined(_LIBCPP_CXX03_LANG)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_REVERSE_ACCESS_H
diff --git a/libcxx/include/__iterator/reverse_iterator.h b/libcxx/include/__iterator/reverse_iterator.h
--- a/libcxx/include/__iterator/reverse_iterator.h
+++ b/libcxx/include/__iterator/reverse_iterator.h
@@ -11,8 +11,8 @@
 #define _LIBCPP___ITERATOR_REVERSE_ITERATOR_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
 #include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
 #include <type_traits>
 
diff --git a/libcxx/include/__iterator/size.h b/libcxx/include/__iterator/size.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__iterator/size.h
@@ -0,0 +1,58 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ITERATOR_SIZE_H
+#define _LIBCPP___ITERATOR_SIZE_H
+
+#include <__config>
+#include <cstddef>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 14
+
+template <class _Cont>
+_LIBCPP_INLINE_VISIBILITY
+constexpr auto size(const _Cont& __c)
+_NOEXCEPT_(noexcept(__c.size()))
+-> decltype        (__c.size())
+{ return            __c.size(); }
+
+template <class _Tp, size_t _Sz>
+_LIBCPP_INLINE_VISIBILITY
+constexpr size_t size(const _Tp (&)[_Sz]) noexcept { return _Sz; }
+
+#if _LIBCPP_STD_VER > 17
+template <class _Cont>
+_LIBCPP_INLINE_VISIBILITY
+constexpr auto ssize(const _Cont& __c)
+_NOEXCEPT_(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size())))
+->                              common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>
+{ return            static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size()); }
+
+template <class _Tp, ptrdiff_t _Sz>
+_LIBCPP_INLINE_VISIBILITY
+constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept { return _Sz; }
+#endif
+
+#endif // _LIBCPP_STD_VER > 14
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ITERATOR_SIZE_H
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -561,27 +561,34 @@
 #include <__config>
 #include <__debug>
 #include <__functional_base>
+#include <__iterator/access.h>
 #include <__iterator/advance.h>
 #include <__iterator/back_insert_iterator.h>
 #include <__iterator/concepts.h>
+#include <__iterator/data.h>
 #include <__iterator/default_sentinel.h>
+#include <__iterator/distance.h>
+#include <__iterator/empty.h>
+#include <__iterator/erase_if_container.h>
 #include <__iterator/front_insert_iterator.h>
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/insert_iterator.h>
-#include <__iterator/istream_iterator.h>
 #include <__iterator/istreambuf_iterator.h>
+#include <__iterator/istream_iterator.h>
+#include <__iterator/iterator.h>
+#include <__iterator/iterator_traits.h>
 #include <__iterator/iter_move.h>
 #include <__iterator/iter_swap.h>
-#include <__iterator/iterator_traits.h>
-#include <__iterator/iterator.h>
 #include <__iterator/move_iterator.h>
 #include <__iterator/next.h>
-#include <__iterator/ostream_iterator.h>
 #include <__iterator/ostreambuf_iterator.h>
+#include <__iterator/ostream_iterator.h>
 #include <__iterator/prev.h>
 #include <__iterator/projected.h>
 #include <__iterator/readable_traits.h>
+#include <__iterator/reverse_access.h>
 #include <__iterator/reverse_iterator.h>
+#include <__iterator/size.h>
 #include <__iterator/wrap_iter.h>
 #include <__memory/addressof.h>
 #include <__memory/pointer_traits.h>
@@ -597,304 +604,4 @@
 #pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-template <class _InputIter>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-typename iterator_traits<_InputIter>::difference_type
-__distance(_InputIter __first, _InputIter __last, input_iterator_tag)
-{
-    typename iterator_traits<_InputIter>::difference_type __r(0);
-    for (; __first != __last; ++__first)
-        ++__r;
-    return __r;
-}
-
-template <class _RandIter>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-typename iterator_traits<_RandIter>::difference_type
-__distance(_RandIter __first, _RandIter __last, random_access_iterator_tag)
-{
-    return __last - __first;
-}
-
-template <class _InputIter>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-typename iterator_traits<_InputIter>::difference_type
-distance(_InputIter __first, _InputIter __last)
-{
-    return _VSTD::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
-}
-
-template <class _Tp, size_t _Np>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp*
-begin(_Tp (&__array)[_Np])
-{
-    return __array;
-}
-
-template <class _Tp, size_t _Np>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp*
-end(_Tp (&__array)[_Np])
-{
-    return __array + _Np;
-}
-
-#if !defined(_LIBCPP_CXX03_LANG)
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto
-begin(_Cp& __c) -> decltype(__c.begin())
-{
-    return __c.begin();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto
-begin(const _Cp& __c) -> decltype(__c.begin())
-{
-    return __c.begin();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto
-end(_Cp& __c) -> decltype(__c.end())
-{
-    return __c.end();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto
-end(const _Cp& __c) -> decltype(__c.end())
-{
-    return __c.end();
-}
-
-#if _LIBCPP_STD_VER > 11
-
-template <class _Tp, size_t _Np>
-_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>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-reverse_iterator<_Tp*> rend(_Tp (&__array)[_Np])
-{
-    return reverse_iterator<_Tp*>(__array);
-}
-
-template <class _Ep>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-reverse_iterator<const _Ep*> rbegin(initializer_list<_Ep> __il)
-{
-    return reverse_iterator<const _Ep*>(__il.end());
-}
-
-template <class _Ep>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-reverse_iterator<const _Ep*> rend(initializer_list<_Ep> __il)
-{
-    return reverse_iterator<const _Ep*>(__il.begin());
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-auto cbegin(const _Cp& __c) -> decltype(_VSTD::begin(__c))
-{
-    return _VSTD::begin(__c);
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-auto cend(const _Cp& __c) -> decltype(_VSTD::end(__c))
-{
-    return _VSTD::end(__c);
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto rbegin(_Cp& __c) -> decltype(__c.rbegin())
-{
-    return __c.rbegin();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto rbegin(const _Cp& __c) -> decltype(__c.rbegin())
-{
-    return __c.rbegin();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto rend(_Cp& __c) -> decltype(__c.rend())
-{
-    return __c.rend();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto rend(const _Cp& __c) -> decltype(__c.rend())
-{
-    return __c.rend();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto crbegin(const _Cp& __c) -> decltype(_VSTD::rbegin(__c))
-{
-    return _VSTD::rbegin(__c);
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-auto crend(const _Cp& __c) -> decltype(_VSTD::rend(__c))
-{
-    return _VSTD::rend(__c);
-}
-
-#endif
-
-
-#else  // defined(_LIBCPP_CXX03_LANG)
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY
-typename _Cp::iterator
-begin(_Cp& __c)
-{
-    return __c.begin();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY
-typename _Cp::const_iterator
-begin(const _Cp& __c)
-{
-    return __c.begin();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY
-typename _Cp::iterator
-end(_Cp& __c)
-{
-    return __c.end();
-}
-
-template <class _Cp>
-_LIBCPP_INLINE_VISIBILITY
-typename _Cp::const_iterator
-end(const _Cp& __c)
-{
-    return __c.end();
-}
-
-#endif // !defined(_LIBCPP_CXX03_LANG)
-
-#if _LIBCPP_STD_VER > 14
-
-// #if _LIBCPP_STD_VER > 11
-// template <>
-// struct _LIBCPP_TEMPLATE_VIS plus<void>
-// {
-//     template <class _T1, class _T2>
-//     _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
-//     auto operator()(_T1&& __t, _T2&& __u) const
-//     _NOEXCEPT_(noexcept(_VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u)))
-//     -> decltype        (_VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u))
-//         { return        _VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u); }
-//     typedef void is_transparent;
-// };
-// #endif
-
-template <class _Cont>
-_LIBCPP_INLINE_VISIBILITY
-constexpr auto size(const _Cont& __c)
-_NOEXCEPT_(noexcept(__c.size()))
--> decltype        (__c.size())
-{ return            __c.size(); }
-
-template <class _Tp, size_t _Sz>
-_LIBCPP_INLINE_VISIBILITY
-constexpr size_t size(const _Tp (&)[_Sz]) noexcept { return _Sz; }
-
-#if _LIBCPP_STD_VER > 17
-template <class _Cont>
-_LIBCPP_INLINE_VISIBILITY
-constexpr auto ssize(const _Cont& __c)
-_NOEXCEPT_(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size())))
-->                              common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>
-{ return            static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size()); }
-
-template <class _Tp, ptrdiff_t _Sz>
-_LIBCPP_INLINE_VISIBILITY
-constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept { return _Sz; }
-#endif
-
-template <class _Cont>
-_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
-constexpr auto empty(const _Cont& __c)
-_NOEXCEPT_(noexcept(__c.empty()))
--> decltype        (__c.empty())
-{ return            __c.empty(); }
-
-template <class _Tp, size_t _Sz>
-_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
-constexpr bool empty(const _Tp (&)[_Sz]) noexcept { return false; }
-
-template <class _Ep>
-_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
-constexpr bool empty(initializer_list<_Ep> __il) noexcept { return __il.size() == 0; }
-
-template <class _Cont> constexpr
-_LIBCPP_INLINE_VISIBILITY
-auto data(_Cont& __c)
-_NOEXCEPT_(noexcept(__c.data()))
--> decltype        (__c.data())
-{ return            __c.data(); }
-
-template <class _Cont> constexpr
-_LIBCPP_INLINE_VISIBILITY
-auto data(const _Cont& __c)
-_NOEXCEPT_(noexcept(__c.data()))
--> decltype        (__c.data())
-{ return            __c.data(); }
-
-template <class _Tp, size_t _Sz>
-_LIBCPP_INLINE_VISIBILITY
-constexpr _Tp* data(_Tp (&__array)[_Sz]) noexcept { return __array; }
-
-template <class _Ep>
-_LIBCPP_INLINE_VISIBILITY
-constexpr const _Ep* data(initializer_list<_Ep> __il) noexcept { return __il.begin(); }
-#endif
-
-template <class _Container, class _Predicate>
-typename _Container::size_type
-__libcpp_erase_if_container(_Container& __c, _Predicate& __pred) {
-  typename _Container::size_type __old_size = __c.size();
-
-  const typename _Container::iterator __last = __c.end();
-  for (typename _Container::iterator __iter = __c.begin(); __iter != __last;) {
-    if (__pred(*__iter))
-      __iter = __c.erase(__iter);
-    else
-      ++__iter;
-  }
-
-  return __old_size - __c.size();
-}
-
-_LIBCPP_END_NAMESPACE_STD
-
 #endif // _LIBCPP_ITERATOR
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -474,28 +474,35 @@
     export *
 
     module __iterator {
-      module advance                { header "__iterator/advance.h"               }
-      module back_insert_iterator   { header "__iterator/back_insert_iterator.h"  }
-      module concepts               { header "__iterator/concepts.h"              }
-      module default_sentinel       { header "__iterator/default_sentinel.h"      }
-      module front_insert_iterator  { header "__iterator/front_insert_iterator.h" }
-      module incrementable_traits   { header "__iterator/incrementable_traits.h"  }
-      module insert_iterator        { header "__iterator/insert_iterator.h"       }
-      module istream_iterator       { header "__iterator/istream_iterator.h"      }
-      module istreambuf_iterator    { header "__iterator/istreambuf_iterator.h"   }
-      module iter_move              { header "__iterator/iter_move.h"             }
-      module iter_swap              { header "__iterator/iter_swap.h"             }
-      module iterator               { header "__iterator/iterator.h"              }
-      module iterator_traits        { header "__iterator/iterator_traits.h"       }
-      module move_iterator          { header "__iterator/move_iterator.h"         }
-      module next                   { header "__iterator/next.h"                  }
-      module ostream_iterator       { header "__iterator/ostream_iterator.h"      }
-      module ostreambuf_iterator    { header "__iterator/ostreambuf_iterator.h"   }
-      module prev                   { header "__iterator/prev.h"                  }
-      module projected              { header "__iterator/projected.h"             }
-      module readable_traits        { header "__iterator/readable_traits.h"       }
-      module reverse_iterator       { header "__iterator/reverse_iterator.h"      }
-      module wrap_iter              { header "__iterator/wrap_iter.h"             }
+      module access                { header "__iterator/access.h" }
+      module advance               { header "__iterator/advance.h" }
+      module back_insert_iterator  { header "__iterator/back_insert_iterator.h" }
+      module concepts              { header "__iterator/concepts.h" }
+      module data                  { header "__iterator/data.h" }
+      module default_sentinel      { header "__iterator/default_sentinel.h" }
+      module distance              { header "__iterator/distance.h" }
+      module empty                 { header "__iterator/empty.h" }
+      module erase_if_container    { header "__iterator/erase_if_container.h" }
+      module front_insert_iterator { header "__iterator/front_insert_iterator.h" }
+      module incrementable_traits  { header "__iterator/incrementable_traits.h" }
+      module insert_iterator       { header "__iterator/insert_iterator.h" }
+      module istreambuf_iterator   { header "__iterator/istreambuf_iterator.h" }
+      module istream_iterator      { header "__iterator/istream_iterator.h" }
+      module iterator              { header "__iterator/iterator.h" }
+      module iterator_traits       { header "__iterator/iterator_traits.h" }
+      module iter_move             { header "__iterator/iter_move.h" }
+      module iter_swap             { header "__iterator/iter_swap.h" }
+      module move_iterator         { header "__iterator/move_iterator.h" }
+      module next                  { header "__iterator/next.h" }
+      module ostreambuf_iterator   { header "__iterator/ostreambuf_iterator.h" }
+      module ostream_iterator      { header "__iterator/ostream_iterator.h" }
+      module prev                  { header "__iterator/prev.h" }
+      module projected             { header "__iterator/projected.h" }
+      module readable_traits       { header "__iterator/readable_traits.h" }
+      module reverse_access        { header "__iterator/reverse_access.h" }
+      module reverse_iterator      { header "__iterator/reverse_iterator.h" }
+      module size                  { header "__iterator/size.h" }
+      module wrap_iter             { header "__iterator/wrap_iter.h" }
     }
   }
   module latch {
diff --git a/libcxx/test/support/test_iterators.h b/libcxx/test/support/test_iterators.h
--- a/libcxx/test/support/test_iterators.h
+++ b/libcxx/test/support/test_iterators.h
@@ -13,6 +13,7 @@
 #include <stdexcept>
 #include <cstddef>
 #include <cassert>
+#include <utility>
 
 #include "test_macros.h"