diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -144,6 +144,7 @@
   ratio
   ranges
   __ranges/access.h
+  __ranges/concepts.h
   regex
   scoped_allocator
   semaphore
diff --git a/libcxx/include/__ranges/concepts.h b/libcxx/include/__ranges/concepts.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__ranges/concepts.h
@@ -0,0 +1,61 @@
+// -*- C++ -*-
+//===-------------------------- concepts ----------------------------------===//
+//
+// 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_RANGES_CONCEPTS_H
+#define _LIBCPP_RANGES_CONCEPTS_H
+
+#include <__config>
+#include <__ranges/access.h>
+#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 !defined(_LIBCPP_HAS_NO_RANGES)
+
+namespace ranges {
+// [range.range]
+template <class _Tp>
+concept range = requires(_Tp& __t) {
+  ranges::begin(__t); // sometimes equality-preserving
+  ranges::end(__t);
+};
+
+// `iterator_t` is repeated in <__ranges/access.h> and <__ranges/concepts.h> for clarity's sake.
+template <class _Tp>
+using iterator_t = decltype(ranges::begin(declval<_Tp&>()));
+
+template <range _Rp>
+using sentinel_t = decltype(ranges::end(declval<_Rp&>()));
+
+template <range R>
+using range_difference_t = iter_difference_t<iterator_t<R> >;
+
+template <range R>
+using range_value_t = iter_value_t<iterator_t<R> >;
+
+template <range R>
+using range_reference_t = iter_reference_t<iterator_t<R> >;
+
+template <range R>
+using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<R> >;
+} // namespace ranges
+
+#endif // !defined(_LIBCPP_HAS_NO_RANGES)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP_RANGES_CONCEPTS_H
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -22,7 +22,22 @@
 //
 //   // [range.range], ranges
 //   template<class T>
+//     concept range = see below;
+//
+//   template<class T>
+//     using iterator_t = decltype(ranges::begin(declval<T&>()));
+//   template<class T>
 //     using iterator_t = decltype(ranges::begin(declval<T&>()));
+//   template<range R>
+//     using sentinel_t = decltype(ranges::end(declval<R&>()));
+//   template<range R>
+//     using range_difference_t = iter_difference_t<iterator_t<R>>;
+//   template<range R>
+//     using range_value_t = iter_value_t<iterator_t<R>>;
+//   template<range R>
+//     using range_reference_t = iter_reference_t<iterator_t<R>>;
+//   template<range R>
+//     using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<R>>;
 // }
 
 #ifndef _LIBCPP_RANGES
@@ -33,5 +48,6 @@
 #include <iterator>             // see [iterator.synopsis]
 
 #include <__ranges/access.h>
+#include <__ranges/concepts.h>
 
 #endif // _LIBCPP_RANGES
diff --git a/libcxx/test/std/ranges/range.range/helper_aliases.compile.pass.cpp b/libcxx/test/std/ranges/range.range/helper_aliases.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/ranges/range.range/helper_aliases.compile.pass.cpp
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: gcc-10
+
+// template<range R>
+// using range_difference_t = iter_difference_t<iterator_t<R>>;
+
+// template<range R>
+// using range_value_t = iter_value_t<iterator_t<R>>;
+
+// template<range R>
+// using range_reference_t = iter_reference_t<iterator_t<R>>;
+
+// template<range R>
+// using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<R>>;
+
+#include <ranges>
+
+#include <concepts>
+#include <deque>
+#include <vector>
+
+#include "test_range.h"
+
+namespace stdr = std::ranges;
+
+static_assert(std::same_as<stdr::range_difference_t<std::vector<int> >,
+                           std::iter_difference_t<stdr::iterator_t<std::vector<int> > > >);
+static_assert(std::same_as<stdr::range_difference_t<range<std::deque<int> > >,
+                           std::iter_difference_t<stdr::iterator_t<std::deque<int> > > >);
+
+static_assert(
+    std::same_as<stdr::range_value_t<std::vector<int> >, std::iter_value_t<stdr::iterator_t<std::vector<int> > > >);
+static_assert(std::same_as<stdr::range_value_t<range<std::deque<int> > >,
+                           std::iter_value_t<stdr::iterator_t<std::deque<int> > > >);
+
+static_assert(std::same_as<stdr::range_reference_t<std::vector<int> >,
+                           std::iter_reference_t<stdr::iterator_t<std::vector<int> > > >);
+static_assert(std::same_as<stdr::range_reference_t<range<std::deque<int> > >,
+                           std::iter_reference_t<stdr::iterator_t<std::deque<int> > > >);
+
+static_assert(std::same_as<stdr::range_rvalue_reference_t<std::vector<int> >,
+                           std::iter_rvalue_reference_t<stdr::iterator_t<std::vector<int> > > >);
+static_assert(std::same_as<stdr::range_rvalue_reference_t<range<std::deque<int> > >,
+                           std::iter_rvalue_reference_t<stdr::iterator_t<std::deque<int> > > >);
diff --git a/libcxx/test/std/ranges/range.range/range.compile.pass.cpp b/libcxx/test/std/ranges/range.range/range.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/ranges/range.range/range.compile.pass.cpp
@@ -0,0 +1,88 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: gcc-10
+
+// template<class T>
+// concept range;
+
+#include <ranges>
+
+#include <array>
+#include <deque>
+#include <forward_list>
+#include <list>
+#include <map>
+#include <set>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "test_range.h"
+
+namespace stdr = std::ranges;
+
+static_assert(stdr::range<std::array<int, 10> >);
+static_assert(stdr::range<std::deque<int> >);
+static_assert(stdr::range<std::forward_list<int> >);
+static_assert(stdr::range<std::list<int> >);
+static_assert(stdr::range<std::map<int, long> >);
+static_assert(stdr::range<std::multimap<int, long> >);
+static_assert(stdr::range<std::multiset<int> >);
+static_assert(stdr::range<std::set<int> >);
+static_assert(stdr::range<std::string>);
+static_assert(stdr::range<std::string_view>);
+static_assert(stdr::range<std::unordered_map<int, long> >);
+static_assert(stdr::range<std::unordered_multimap<int, long> >);
+static_assert(stdr::range<std::unordered_multiset<int> >);
+static_assert(stdr::range<std::unordered_set<int> >);
+static_assert(stdr::range<std::vector<int> >);
+
+static_assert(stdr::range<range<std::array<int, 10> > >);
+static_assert(stdr::range<range<std::deque<int> > >);
+static_assert(stdr::range<range<std::forward_list<int> > >);
+static_assert(stdr::range<range<std::list<int> > >);
+static_assert(stdr::range<range<std::map<int, long> > >);
+static_assert(stdr::range<range<std::multimap<int, long> > >);
+static_assert(stdr::range<range<std::multiset<int> > >);
+static_assert(stdr::range<range<std::set<int> > >);
+static_assert(stdr::range<range<std::string> >);
+static_assert(stdr::range<range<std::string_view> >);
+static_assert(stdr::range<range<std::unordered_map<int, long> > >);
+static_assert(stdr::range<range<std::unordered_multimap<int, long> > >);
+static_assert(stdr::range<range<std::unordered_multiset<int> > >);
+static_assert(stdr::range<range<std::unordered_set<int> > >);
+static_assert(stdr::range<range<std::vector<int> > >);
+
+struct incompatible_iterators {
+  std::vector<int>::iterator begin();
+  std::deque<int>::iterator end();
+};
+static_assert(!stdr::range<incompatible_iterators>);
+
+struct int_begin_int_end {
+  int begin();
+  int end();
+};
+static_assert(!stdr::range<int_begin_int_end>);
+
+struct iterator_begin_int_end {
+  std::vector<int>::iterator begin();
+  int end();
+};
+static_assert(!stdr::range<iterator_begin_int_end>);
+
+struct int_begin_iterator_end {
+  int begin();
+  std::vector<int>::iterator end();
+};
+static_assert(!stdr::range<int_begin_iterator_end>);
diff --git a/libcxx/test/std/ranges/range.range/sentinel_t.compile.pass.cpp b/libcxx/test/std/ranges/range.range/sentinel_t.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/ranges/range.range/sentinel_t.compile.pass.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: gcc-10
+
+// template<range _Rp>
+// using sentinel_t = decltype(ranges::end(declval<_Rp&>()));
+
+#include <ranges>
+
+#include <concepts>
+#include <forward_list>
+#include <iterator>
+#include <list>
+#include <deque>
+#include <vector>
+
+#include "test_range.h"
+
+namespace stdr = std::ranges;
+
+static_assert(std::same_as<stdr::sentinel_t<std::forward_list<int> >, std::forward_list<int>::iterator>);
+static_assert(std::same_as<stdr::sentinel_t<std::forward_list<int> const>, std::forward_list<int>::const_iterator>);
+
+static_assert(std::same_as<stdr::sentinel_t<std::deque<int> >, std::deque<int>::iterator>);
+static_assert(std::same_as<stdr::sentinel_t<std::deque<int> const>, std::deque<int>::const_iterator>);
+
+static_assert(std::same_as<stdr::sentinel_t<std::list<int> >, std::list<int>::iterator>);
+static_assert(std::same_as<stdr::sentinel_t<std::list<int> const>, std::list<int>::const_iterator>);
+
+static_assert(std::same_as<stdr::sentinel_t<std::vector<int> >, std::vector<int>::iterator>);
+static_assert(std::same_as<stdr::sentinel_t<std::vector<int> const>, std::vector<int>::const_iterator>);
+
+static_assert(std::same_as<stdr::sentinel_t<range<std::forward_list<int> > >, sentinel>);
+static_assert(std::same_as<stdr::sentinel_t<range<std::forward_list<int> const> >, sentinel>);
+
+static_assert(std::same_as<stdr::sentinel_t<range<std::deque<int> > >, sentinel>);
+static_assert(std::same_as<stdr::sentinel_t<range<std::deque<int> const> >, sentinel>);
+
+static_assert(std::same_as<stdr::sentinel_t<range<std::list<int> > >, sentinel>);
+static_assert(std::same_as<stdr::sentinel_t<range<std::list<int> const> >, sentinel>);
+
+static_assert(std::same_as<stdr::sentinel_t<range<std::vector<int> > >, sentinel>);
+static_assert(std::same_as<stdr::sentinel_t<range<std::vector<int> const> >, sentinel>);
diff --git a/libcxx/test/support/test_range.h b/libcxx/test/support/test_range.h
new file mode 100644
--- /dev/null
+++ b/libcxx/test/support/test_range.h
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 LIBCXX_TEST_SUPPORT_TEST_RANGE_H
+#define LIBCXX_TEST_SUPPORT_TEST_RANGE_H
+
+#include <ranges>
+
+#ifdef _LIBCPP_HAS_NO_RANGES
+#error "test/suppoort/test_range.h" can only be included in builds supporting ranges
+#endif
+
+struct sentinel {
+  bool operator==(std::input_or_output_iterator auto) const;
+};
+
+template <class R>
+struct range {
+  std::ranges::iterator_t<R> begin();
+  std::ranges::iterator_t<R const> begin() const;
+  sentinel end();
+  sentinel end() const;
+};
+
+#endif // LIBCXX_TEST_SUPPORT_TEST_RANGE_H