diff --git a/libcxx/include/__format/buffer.h b/libcxx/include/__format/buffer.h
--- a/libcxx/include/__format/buffer.h
+++ b/libcxx/include/__format/buffer.h
@@ -159,13 +159,65 @@
   _OutIt __out_it_;
 };
 
+/// Concept to see whether a \a _Container is insertable.
+///
+/// The concept is used to validate whether multiple calls to a
+/// \ref back_insert_iterator can be replaced by a call to \c _Container::insert.
+///
+/// \note a \a _Container needs to opt into the concept by adding a typedef
+/// \ref __enable_format_insertable with the same type as \a _Container.
+template <class _Container>
+concept __insertable =
+    same_as<_Container, typename _Container::__enable_format_insertable> &&
+    __formatter::__char_type<typename _Container::value_type> &&
+    requires(_Container& __t, typename _Container::value_type* __first,
+             typename _Container::value_type* __last) {
+  __t.insert(__t.end(), __first, __last);
+};
+
+/// Extract the container type of a \ref back_insert_iterator.
+template <class _It>
+struct _LIBCPP_TEMPLATE_VIS __back_insert_iterator_container {
+  using type = void;
+};
+
+template <__insertable _Container>
+struct _LIBCPP_TEMPLATE_VIS
+    __back_insert_iterator_container<back_insert_iterator<_Container>> {
+  using type = _Container;
+};
+
+/// Write policy for inserting the buffer in a container.
+template <class _Container>
+class _LIBCPP_TEMPLATE_VIS __writer_container {
+public:
+  using _CharT = typename _Container::value_type;
+
+  _LIBCPP_HIDE_FROM_ABI explicit __writer_container(
+      back_insert_iterator<_Container> __out_it)
+      : __container_{__out_it.__get_container()} {}
+
+  _LIBCPP_HIDE_FROM_ABI auto out() { return back_inserter(*__container_); }
+
+  _LIBCPP_HIDE_FROM_ABI void flush(_CharT* __ptr, size_t __size) {
+    __container_->insert(__container_->end(), __ptr, __ptr + __size);
+  }
+
+private:
+  _Container* __container_;
+};
+
 /// Selects the type of the writer used for the output iterator.
 template <class _OutIt, class _CharT>
 class _LIBCPP_TEMPLATE_VIS __writer_selector {
+  using _Container = typename __back_insert_iterator_container<_OutIt>::type;
+
 public:
-  using type = conditional_t<__enable_direct_output<_OutIt, _CharT>,
-                             __writer_direct<_OutIt, _CharT>,
-                             __writer_iterator<_OutIt, _CharT>>;
+  using type =
+      conditional_t<!same_as<_Container, void>, __writer_container<_Container>,
+                    conditional_t<__enable_direct_output<_OutIt, _CharT>,
+                                  __writer_direct<_OutIt, _CharT>,
+                                  __writer_iterator<_OutIt, _CharT>>>;
 };
 
 /// The generic formatting buffer.
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
@@ -55,6 +55,8 @@
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 back_insert_iterator& operator*()     {return *this;}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 back_insert_iterator& operator++()    {return *this;}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 back_insert_iterator  operator++(int) {return *this;}
+    // This is not part of this patch but D110573.
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 _Container* __get_container() const { return container; }
 };
 
 template <class _Container>
diff --git a/libcxx/include/deque b/libcxx/include/deque
--- a/libcxx/include/deque
+++ b/libcxx/include/deque
@@ -1273,6 +1273,7 @@
     typedef typename __base::const_pointer                           const_pointer;
     typedef _VSTD::reverse_iterator<iterator>                        reverse_iterator;
     typedef _VSTD::reverse_iterator<const_iterator>                  const_reverse_iterator;
+    typedef deque<_Tp, _Allocator>                                   __enable_format_insertable;
 
     using typename __base::__deque_range;
     using typename __base::__deque_block_range;
diff --git a/libcxx/include/list b/libcxx/include/list
--- a/libcxx/include/list
+++ b/libcxx/include/list
@@ -864,6 +864,7 @@
 #else
     typedef void                                                     __remove_return_type;
 #endif
+    typedef list<_Tp, _Alloc>                                        __enable_format_insertable;
 
     _LIBCPP_INLINE_VISIBILITY
     list()
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -692,6 +692,7 @@
     typedef const value_type&                            const_reference;
     typedef typename __alloc_traits::pointer             pointer;
     typedef typename __alloc_traits::const_pointer       const_pointer;
+    typedef basic_string<_CharT, _Traits, _Allocator>    __enable_format_insertable;
 
     static_assert((!is_array<value_type>::value), "Character type of basic_string must not be an array");
     static_assert(( is_standard_layout<value_type>::value), "Character type of basic_string must be standard-layout");
diff --git a/libcxx/include/vector b/libcxx/include/vector
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -366,7 +366,8 @@
     typedef __wrap_iter<pointer>                                     iterator;
     typedef __wrap_iter<const_pointer>                               const_iterator;
     typedef _VSTD::reverse_iterator<iterator>                        reverse_iterator;
-    typedef _VSTD::reverse_iterator<const_iterator>  const_reverse_iterator;
+    typedef _VSTD::reverse_iterator<const_iterator>                  const_reverse_iterator;
+    typedef vector<_Tp, _Allocator>                                  __enable_format_insertable;
 
     static_assert((is_same<typename allocator_type::value_type, value_type>::value),
                   "Allocator::value_type must be same type as value_type");
diff --git a/libcxx/test/libcxx/utilities/format/enable_insertable.compile.pass.cpp b/libcxx/test/libcxx/utilities/format/enable_insertable.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/format/enable_insertable.compile.pass.cpp
@@ -0,0 +1,132 @@
+//===----------------------------------------------------------------------===//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: libcpp-has-no-incomplete-format
+
+// <format>
+
+#include <format>
+#include <array>
+#include <deque>
+#include <forward_list>
+#include <list>
+#include <map>
+#include <queue>
+#include <set>
+#include <span>
+#include <stack>
+#include <string>
+#include <string_view>
+
+#include "test_macros.h"
+
+template <class CharT>
+struct no_value_type {
+  using __enable_format_insertable = no_value_type<CharT>;
+  using iterator = CharT*;
+  iterator end();
+  void insert(iterator, CharT*, CharT*);
+};
+
+template <class CharT>
+struct no_end {
+  using __enable_format_insertable = no_end<CharT>;
+  using value_type = CharT;
+  using iterator = CharT*;
+  void insert(iterator, CharT*, CharT*);
+};
+
+template <class CharT>
+struct no_insert {
+  using __enable_format_insertable = no_insert<CharT>;
+  using value_type = CharT;
+  using iterator = CharT*;
+  iterator end();
+};
+
+template <class CharT>
+struct no_specialization {
+  using value_type = CharT;
+  using iterator = CharT*;
+  iterator end();
+  void insert(iterator, CharT*, CharT*);
+};
+
+template <class CharT>
+struct valid {
+  using __enable_format_insertable = valid<CharT>;
+  using value_type = CharT;
+  using iterator = CharT*;
+  iterator end();
+  void insert(iterator, CharT*, CharT*);
+};
+
+static_assert(!std::__format::__insertable<no_value_type<char>>);
+static_assert(!std::__format::__insertable<no_end<char>>);
+static_assert(!std::__format::__insertable<no_insert<char>>);
+static_assert(!std::__format::__insertable<no_specialization<char>>);
+static_assert(std::__format::__insertable<valid<char>>);
+
+static_assert(std::__format::__insertable<std::string>);
+static_assert(!std::__format::__insertable<std::string_view>);
+
+static_assert(!std::__format::__insertable<std::array<char, 1>>);
+
+static_assert(std::__format::__insertable<std::vector<char>>);
+static_assert(std::__format::__insertable<std::deque<char>>);
+static_assert(!std::__format::__insertable<std::forward_list<char>>);
+static_assert(std::__format::__insertable<std::list<char>>);
+
+static_assert(!std::__format::__insertable<std::set<char>>);
+static_assert(!std::__format::__insertable<std::map<char, char>>);
+static_assert(!std::__format::__insertable<std::multiset<char>>);
+static_assert(!std::__format::__insertable<std::multimap<char, char>>);
+
+static_assert(!std::__format::__insertable<std::stack<char>>);
+static_assert(!std::__format::__insertable<std::queue<char>>);
+static_assert(!std::__format::__insertable<std::priority_queue<char>>);
+
+static_assert(!std::__format::__insertable<std::span<char>>);
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(!std::__format::__insertable<no_value_type<wchar_t>>);
+static_assert(!std::__format::__insertable<no_end<wchar_t>>);
+static_assert(!std::__format::__insertable<no_insert<wchar_t>>);
+static_assert(!std::__format::__insertable<no_specialization<wchar_t>>);
+static_assert(std::__format::__insertable<valid<wchar_t>>);
+
+static_assert(std::__format::__insertable<std::wstring>);
+static_assert(!std::__format::__insertable<std::wstring_view>);
+
+static_assert(!std::__format::__insertable<std::array<wchar_t, 1>>);
+
+static_assert(std::__format::__insertable<std::vector<wchar_t>>);
+static_assert(std::__format::__insertable<std::deque<wchar_t>>);
+static_assert(!std::__format::__insertable<std::forward_list<wchar_t>>);
+static_assert(std::__format::__insertable<std::list<wchar_t>>);
+
+static_assert(!std::__format::__insertable<std::set<wchar_t>>);
+static_assert(!std::__format::__insertable<std::map<wchar_t, wchar_t>>);
+static_assert(!std::__format::__insertable<std::multiset<wchar_t>>);
+static_assert(!std::__format::__insertable<std::multimap<wchar_t, wchar_t>>);
+
+static_assert(!std::__format::__insertable<std::stack<wchar_t>>);
+static_assert(!std::__format::__insertable<std::queue<wchar_t>>);
+static_assert(!std::__format::__insertable<std::priority_queue<wchar_t>>);
+
+static_assert(!std::__format::__insertable<std::span<wchar_t>>);
+#endif
+
+static_assert(!std::__format::__insertable<valid<signed char>>);
+static_assert(!std::__format::__insertable<valid<unsigned char>>);
+
+struct UserVector : public std::vector<char> {
+  using std::vector<char>::vector;
+};
+static_assert(!std::__format::__insertable<UserVector>);