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
@@ -11,12 +11,16 @@
 #define _LIBCPP___FORMAT_BUFFER_H
 
 #include <__algorithm/copy_n.h>
+#include <__algorithm/max.h>
+#include <__algorithm/min.h>
 #include <__algorithm/unwrap_iter.h>
 #include <__config>
 #include <__format/enable_insertable.h>
+#include <__format/format_to_n_result.h>
 #include <__format/formatter.h> // for __char_type TODO FMT Move the concept?
 #include <__iterator/back_insert_iterator.h>
 #include <__iterator/concepts.h>
+#include <__iterator/incrementable_traits.h>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/wrap_iter.h>
 #include <__utility/move.h>
@@ -28,6 +32,9 @@
 #  pragma GCC system_header
 #endif
 
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if _LIBCPP_STD_VER > 17
@@ -267,10 +274,97 @@
   size_t __size_{0};
 };
 
+/// The base of a buffer that counts and limits the number of insertions.
+template <class _OutIt, __formatter::__char_type _CharT, bool>
+  requires(output_iterator<_OutIt, const _CharT&>)
+struct _LIBCPP_TEMPLATE_VIS __format_to_n_buffer_base {
+  using _Size = iter_difference_t<_OutIt>;
+
+public:
+  _LIBCPP_HIDE_FROM_ABI explicit __format_to_n_buffer_base(_OutIt __out_it, _Size __n)
+      : __writer_(_VSTD::move(__out_it)), __n_(_VSTD::max(_Size(0), __n)) {}
+
+  _LIBCPP_HIDE_FROM_ABI void flush(_CharT* __ptr, size_t __size) {
+    if (_Size(__size_) <= __n_)
+      __writer_.flush(__ptr, _VSTD::min(_Size(__size), __n_ - __size_));
+    __size_ += __size;
+  }
+
+protected:
+  __internal_storage<_CharT> __storage_;
+  __output_buffer<_CharT> __output_{__storage_.begin(), __storage_.capacity(), this};
+  typename __writer_selector<_OutIt, _CharT>::type __writer_;
+
+  _Size __n_;
+  _Size __size_{0};
+};
+
+/// The base of a buffer that counts and limits the number of insertions.
+///
+/// This version is used when \c __enable_direct_output<_OutIt, _CharT> == true.
+///
+/// This class limits the size available the the direct writer so it will not
+/// exceed the maximum number of code units.
+template <class _OutIt, __formatter::__char_type _CharT>
+  requires(output_iterator<_OutIt, const _CharT&>)
+class _LIBCPP_TEMPLATE_VIS __format_to_n_buffer_base<_OutIt, _CharT, true> {
+  using _Size = iter_difference_t<_OutIt>;
+
+public:
+  _LIBCPP_HIDE_FROM_ABI explicit __format_to_n_buffer_base(_OutIt __out_it, _Size __n)
+      : __output_(_VSTD::__unwrap_iter(__out_it), __n, this), __writer_(_VSTD::move(__out_it)) {
+    if (__n <= 0) [[unlikely]]
+      __output_.reset(__storage_.begin(), __storage_.capacity());
+  }
+
+  _LIBCPP_HIDE_FROM_ABI void flush(_CharT* __ptr, size_t __size) {
+    // A flush to the direct writer happens in two occasions:
+    // - The format function has written the maximum number of allowed code
+    //   units. At this point it's no longer valid to write to this writer. So
+    //   switch to the internal storage. This internal storage doesn't need to
+    //   be written anywhere so the flush for that storage writes no output.
+    // - The format_to_n function is finished. In this case there's no need to
+    //   switch the buffer, but for simplicity the buffers are still switched.
+    // When the __n <= 0 the constructor already switched the buffers.
+    if (__size_ == 0 && __ptr != __storage_.begin()) {
+      __writer_.flush(__ptr, __size);
+      __output_.reset(__storage_.begin(), __storage_.capacity());
+    }
+
+    __size_ += __size;
+  }
+
+protected:
+  __internal_storage<_CharT> __storage_;
+  __output_buffer<_CharT> __output_;
+  __writer_direct<_OutIt, _CharT> __writer_;
+
+  _Size __size_{0};
+};
+
+/// The buffer that counts and limits the number of insertions.
+template <class _OutIt, __formatter::__char_type _CharT>
+  requires(output_iterator<_OutIt, const _CharT&>)
+struct _LIBCPP_TEMPLATE_VIS __format_to_n_buffer final
+    : public __format_to_n_buffer_base< _OutIt, _CharT, __enable_direct_output<_OutIt, _CharT>> {
+  using _Base = __format_to_n_buffer_base<_OutIt, _CharT, __enable_direct_output<_OutIt, _CharT>>;
+  using _Size = iter_difference_t<_OutIt>;
+
+public:
+  _LIBCPP_HIDE_FROM_ABI explicit __format_to_n_buffer(_OutIt __out_it, _Size __n) : _Base(_VSTD::move(__out_it), __n) {}
+  _LIBCPP_HIDE_FROM_ABI auto make_output_iterator() { return this->__output_.make_output_iterator(); }
+
+  _LIBCPP_HIDE_FROM_ABI format_to_n_result<_OutIt> result() && {
+    this->__output_.flush();
+    return {_VSTD::move(this->__writer_).out(), this->__size_};
+  }
+};
 } // namespace __format
 
 #endif //_LIBCPP_STD_VER > 17
 
 _LIBCPP_END_NAMESPACE_STD
 
+_LIBCPP_POP_MACROS
+
 #endif // _LIBCPP___FORMAT_BUFFER_H
diff --git a/libcxx/include/format b/libcxx/include/format
--- a/libcxx/include/format
+++ b/libcxx/include/format
@@ -309,6 +309,9 @@
   }
 }
 
+// The function is _LIBCPP_ALWAYS_INLINE since the compiler is bad at inlining
+// https://reviews.llvm.org/D110499#inline-1180704
+// TODO FMT Evaluate whether we want to file a Clang bug report regarding this.
 template <output_iterator<const char&> _OutIt>
 _LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt
 vformat_to(_OutIt __out_it, string_view __fmt, format_args __args) {
@@ -369,31 +372,27 @@
 }
 #endif
 
+template <class _Context, class _OutIt, class _CharT>
+_LIBCPP_HIDE_FROM_ABI format_to_n_result<_OutIt> __vformat_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n,
+                                                                basic_string_view<_CharT> __fmt,
+                                                                basic_format_args<_Context> __args) {
+  __format::__format_to_n_buffer<_OutIt, _CharT> __buffer{_VSTD::move(__out_it), __n};
+  _VSTD::__format::__vformat_to(basic_format_parse_context{__fmt, __args.__size()},
+                                _VSTD::__format_context_create(__buffer.make_output_iterator(), __args));
+  return _VSTD::move(__buffer).result();
+}
+
 template <output_iterator<const char&> _OutIt, class... _Args>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
-format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, string_view __fmt,
-            const _Args&... __args) {
-  // TODO FMT Improve PoC: using std::string is inefficient.
-  string __str = _VSTD::vformat(__fmt, _VSTD::make_format_args(__args...));
-  iter_difference_t<_OutIt> __s = __str.size();
-  iter_difference_t<_OutIt> __m =
-      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
-  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
-  return {_VSTD::move(__out_it), __s};
+_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
+format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, string_view __fmt, const _Args&... __args) {
+  return _VSTD::__vformat_to_n<format_context>(_VSTD::move(__out_it), __n, __fmt, _VSTD::make_format_args(__args...));
 }
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 template <output_iterator<const wchar_t&> _OutIt, class... _Args>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
-format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, wstring_view __fmt,
-            const _Args&... __args) {
-  // TODO FMT Improve PoC: using std::string is inefficient.
-  wstring __str = _VSTD::vformat(__fmt, _VSTD::make_wformat_args(__args...));
-  iter_difference_t<_OutIt> __s = __str.size();
-  iter_difference_t<_OutIt> __m =
-      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
-  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
-  return {_VSTD::move(__out_it), __s};
+_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
+format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, wstring_view __fmt, const _Args&... __args) {
+  return _VSTD::__vformat_to_n<wformat_context>(_VSTD::move(__out_it), __n, __fmt, _VSTD::make_wformat_args(__args...));
 }
 #endif
 
@@ -507,33 +506,30 @@
 }
 #endif
 
+template <class _Context, class _OutIt, class _CharT>
+_LIBCPP_HIDE_FROM_ABI format_to_n_result<_OutIt> __vformat_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n,
+                                                                locale __loc, basic_string_view<_CharT> __fmt,
+                                                                basic_format_args<_Context> __args) {
+  __format::__format_to_n_buffer<_OutIt, _CharT> __buffer{_VSTD::move(__out_it), __n};
+  _VSTD::__format::__vformat_to(
+      basic_format_parse_context{__fmt, __args.__size()},
+      _VSTD::__format_context_create(__buffer.make_output_iterator(), __args, _VSTD::move(__loc)));
+  return _VSTD::move(__buffer).result();
+}
+
 template <output_iterator<const char&> _OutIt, class... _Args>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
-format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, locale __loc,
-            string_view __fmt, const _Args&... __args) {
-  // TODO FMT Improve PoC: using std::string is inefficient.
-  string __str = _VSTD::vformat(_VSTD::move(__loc), __fmt,
-                                _VSTD::make_format_args(__args...));
-  iter_difference_t<_OutIt> __s = __str.size();
-  iter_difference_t<_OutIt> __m =
-      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
-  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
-  return {_VSTD::move(__out_it), __s};
+_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
+format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, locale __loc, string_view __fmt, const _Args&... __args) {
+  return _VSTD::__vformat_to_n<format_context>(_VSTD::move(__out_it), __n, _VSTD::move(__loc), __fmt,
+                                               _VSTD::make_format_args(__args...));
 }
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 template <output_iterator<const wchar_t&> _OutIt, class... _Args>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
-format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, locale __loc,
-            wstring_view __fmt, const _Args&... __args) {
-  // TODO FMT Improve PoC: using std::string is inefficient.
-  wstring __str = _VSTD::vformat(_VSTD::move(__loc), __fmt,
-                                 _VSTD::make_wformat_args(__args...));
-  iter_difference_t<_OutIt> __s = __str.size();
-  iter_difference_t<_OutIt> __m =
-      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
-  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
-  return {_VSTD::move(__out_it), __s};
+_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
+format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, locale __loc, wstring_view __fmt, const _Args&... __args) {
+  return _VSTD::__vformat_to_n<wformat_context>(_VSTD::move(__out_it), __n, _VSTD::move(__loc), __fmt,
+                                                _VSTD::make_wformat_args(__args...));
 }
 #endif