diff --git a/libcxx/docs/Status/RangesAlgorithms.csv b/libcxx/docs/Status/RangesAlgorithms.csv
--- a/libcxx/docs/Status/RangesAlgorithms.csv
+++ b/libcxx/docs/Status/RangesAlgorithms.csv
@@ -27,8 +27,8 @@
 Search,search_n,Not assigned,n/a,Not started
 Search,find_end,Not assigned,n/a,Not started
 Read-only,is_partitioned,Nikolas Klauser,`D124440 <https://llvm.org/D124440>`_,✅
-Read-only,is_sorted,Not assigned,n/a,Not started
-Read-only,is_sorted_unitl,Not assigned,n/a,Not started
+Read-only,is_sorted,Nikolas Klauser,` <https://llvm.org/>`_,✅
+Read-only,is_sorted_unitl,Nikolas Klauser,` <https://llvm.org/>`_,✅
 Read-only,includes,Not assigned,n/a,Not started
 Read-only,is_heap,Not assigned,n/a,Not started
 Read-only,is_heap_until,Not assigned,n/a,Not started
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -78,6 +78,8 @@
   __algorithm/ranges_for_each.h
   __algorithm/ranges_for_each_n.h
   __algorithm/ranges_is_partitioned.h
+  __algorithm/ranges_is_sorted.h
+  __algorithm/ranges_is_sorted_until.h
   __algorithm/ranges_max.h
   __algorithm/ranges_max_element.h
   __algorithm/ranges_min.h
diff --git a/libcxx/include/__algorithm/ranges_is_sorted.h b/libcxx/include/__algorithm/ranges_is_sorted.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__algorithm/ranges_is_sorted.h
@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// 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__ALGORIUTHM_RANGES_IS_SORTED_H
+#define _LIBCPP__ALGORIUTHM_RANGES_IS_SORTED_H
+
+#include <__algorithm/ranges_is_sorted_until.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/projected.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER > 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+namespace __is_sorted {
+struct __fn {
+  template <forward_iterator _Iter, sentinel_for<_Iter> _Sent,
+            class _Proj = identity,
+            indirect_strict_weak_order<projected<_Iter, _Proj>> _Comp = ranges::less>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  bool operator()(_Iter __first, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
+    return ranges::__is_sorted_until_impl(__first, __last, __comp, __proj) == __last;
+  }
+
+  template <forward_range _Range,
+            class _Proj = identity,
+            indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::less>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  bool operator()(_Range&& __range, _Comp __comp = {}, _Proj __proj = {}) const {
+    return ranges::__is_sorted_until_impl(ranges::begin(__range),
+                                          ranges::end(__range),
+                                          __comp,
+                                          __proj) == ranges::end(__range);
+  }
+};
+} // namespace __is_sorted
+
+inline namespace __cpo {
+  inline constexpr auto is_sorted = __is_sorted::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17
+
+#endif // _LIBCPP__ALGORIUTHM_RANGES_IS_SORTED_H
diff --git a/libcxx/include/__algorithm/ranges_is_sorted_until.h b/libcxx/include/__algorithm/ranges_is_sorted_until.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__algorithm/ranges_is_sorted_until.h
@@ -0,0 +1,76 @@
+//===----------------------------------------------------------------------===//
+//
+// 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__ALGORIUTHM_RANGES_IS_SORTED_UNTIL_H
+#define _LIBCPP__ALGORIUTHM_RANGES_IS_SORTED_UNTIL_H
+
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER > 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+
+template <class _Iter, class _Sent, class _Proj, class _Comp>
+_LIBCPP_HIDE_FROM_ABI constexpr
+_Iter __is_sorted_until_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
+  if (__first == __last)
+    return __first;
+  auto __i = __first;
+  while (++__i != __last) {
+    if (std::invoke(__comp, std::invoke(__proj, *__i), std::invoke(__proj, *__first)))
+      return __i;
+    __first = std::move(__i);
+  }
+  return std::move(__i);
+}
+
+namespace __is_sorted_until {
+struct __fn {
+  template <forward_iterator _Iter, sentinel_for<_Iter> _Sent,
+            class _Proj = identity,
+            indirect_strict_weak_order<projected<_Iter, _Proj>> _Comp = ranges::less>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  _Iter operator()(_Iter __first, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
+    return ranges::__is_sorted_until_impl(__first, __last, __comp, __proj);
+  }
+
+  template <forward_range _Range,
+            class _Proj = identity,
+            indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::less>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  borrowed_iterator_t<_Range> operator()(_Range&& __range, _Comp __comp = {}, _Proj __proj = {}) const {
+    return ranges::__is_sorted_until_impl(ranges::begin(__range), ranges::end(__range), __comp, __proj);
+  }
+};
+} // namespace __is_sorted_until
+
+inline namespace __cpo {
+  inline constexpr auto is_sorted_until = __is_sorted_until::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17
+
+#endif // _LIBCPP__ALGORIUTHM_RANGES_IS_SORTED_UNTIL_H
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -993,6 +993,8 @@
 #include <__algorithm/ranges_for_each.h>
 #include <__algorithm/ranges_for_each_n.h>
 #include <__algorithm/ranges_is_partitioned.h>
+#include <__algorithm/ranges_is_sorted.h>
+#include <__algorithm/ranges_is_sorted_until.h>
 #include <__algorithm/ranges_max.h>
 #include <__algorithm/ranges_max_element.h>
 #include <__algorithm/ranges_min.h>
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -311,6 +311,8 @@
       module ranges_for_each          { private header "__algorithm/ranges_for_each.h" }
       module ranges_for_each_n        { private header "__algorithm/ranges_for_each_n.h" }
       module ranges_is_partitioned    { private header "__algorithm/ranges_is_partitioned.h" }
+      module ranges_is_sorted         { private header "__algorithm/ranges_is_sorted.h" }
+      module ranges_is_sorted_until   { private header "__algorithm/ranges_is_sorted_until.h" }
       module ranges_max               { private header "__algorithm/ranges_max.h" }
       module ranges_max_element       { private header "__algorithm/ranges_max_element.h" }
       module ranges_min               { private header "__algorithm/ranges_min.h" }
diff --git a/libcxx/test/libcxx/private_headers.verify.cpp b/libcxx/test/libcxx/private_headers.verify.cpp
--- a/libcxx/test/libcxx/private_headers.verify.cpp
+++ b/libcxx/test/libcxx/private_headers.verify.cpp
@@ -115,6 +115,8 @@
 #include <__algorithm/ranges_for_each.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_for_each.h'}}
 #include <__algorithm/ranges_for_each_n.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_for_each_n.h'}}
 #include <__algorithm/ranges_is_partitioned.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_is_partitioned.h'}}
+#include <__algorithm/ranges_is_sorted.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_is_sorted.h'}}
+#include <__algorithm/ranges_is_sorted_until.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_is_sorted_until.h'}}
 #include <__algorithm/ranges_max.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_max.h'}}
 #include <__algorithm/ranges_max_element.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_max_element.h'}}
 #include <__algorithm/ranges_min.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_min.h'}}
diff --git a/libcxx/test/std/algorithms/alg.sorting/alg.sort/is.sorted/ranges.is_sorted.pass.cpp b/libcxx/test/std/algorithms/alg.sorting/alg.sort/is.sorted/ranges.is_sorted.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.sorting/alg.sort/is.sorted/ranges.is_sorted.pass.cpp
@@ -0,0 +1,136 @@
+//===----------------------------------------------------------------------===//
+//
+// 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-has-no-incomplete-ranges
+
+// <algorithm>
+
+// template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
+//          indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
+//   constexpr bool ranges::is_sorted(I first, S last, Comp comp = {}, Proj proj = {});
+// template<forward_range R, class Proj = identity,
+//          indirect_strict_weak_order<projected<iterator_t<R>, Proj>> Comp = ranges::less>
+//   constexpr bool ranges::is_sorted(R&& r, Comp comp = {}, Proj proj = {});
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <concepts>
+#include <functional>
+#include <ranges>
+
+#include "test_iterators.h"
+
+template <class Iter, class Sent = Iter>
+constexpr void test_iterators() {
+  { // simple test
+    {
+      int a[] = {1, 2, 3, 4, 3};
+      std::same_as<bool> auto ret = std::ranges::is_sorted(Iter(a), Sent(Iter(a + 5)));
+      assert(!ret);
+    }
+    {
+      int a[] = {1, 2, 3, 4, 3};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+      std::same_as<bool> auto ret = std::ranges::is_sorted(range);
+      assert(!ret);
+    }
+  }
+
+  { // second element isn't sorted
+    {
+      int a[] = {1, 0, 3, 4, 3};
+      auto ret = std::ranges::is_sorted(Iter(a), Sent(Iter(a + 5)));
+      assert(!ret);
+    }
+    {
+      int a[] = {1, 0, 3, 4, 3};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+      auto ret = std::ranges::is_sorted(range);
+      assert(!ret);
+    }
+  }
+
+  { // all elements are sorted
+    {
+      int a[] = {1, 2, 3, 4, 5};
+      auto ret = std::ranges::is_sorted(Iter(a), Sent(Iter(a + 5)));
+      assert(ret);
+    }
+    {
+      int a[] = {1, 2, 3, 4, 5};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+      auto ret = std::ranges::is_sorted(range);
+      assert(ret);
+    }
+  }
+
+  { // check that the comparator is used
+    {
+      int a[] = {5, 4, 3, 2};
+      auto ret = std::ranges::is_sorted(Iter(a), Sent(Iter(a + 4)), std::ranges::greater{});
+      assert(ret);
+    }
+    {
+      int a[] = {5, 4, 3, 2};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 4)));
+      auto ret = std::ranges::is_sorted(range, std::ranges::greater{});
+      assert(ret);
+    }
+  }
+
+  { // check that an empty range works
+    {
+      int a[] = {};
+      auto ret = std::ranges::is_sorted(Iter(a), Sent(Iter(a)));
+      assert(ret);
+    }
+    {
+      int a[] = {};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a)));
+      auto ret = std::ranges::is_sorted(range);
+      assert(ret);
+    }
+  }
+}
+
+constexpr bool test() {
+  test_iterators<forward_iterator<int*>>();
+  test_iterators<bidirectional_iterator<int*>>();
+  test_iterators<random_access_iterator<int*>>();
+  test_iterators<contiguous_iterator<int*>>();
+  test_iterators<int*>();
+  test_iterators<const int*>();
+
+  { // check that the comparator is used
+    struct S {
+      int i;
+      constexpr S(int i_) : i(i_) {}
+    };
+    {
+      S a[] = {1, 2, 3};
+      auto ret = std::ranges::is_sorted(a, a + 3, {}, &S::i);
+      assert(ret);
+    }
+    {
+      S a[] = {1, 2, 3};
+      auto ret = std::ranges::is_sorted(a, {}, &S::i);
+      assert(ret);
+    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/algorithms/alg.sorting/alg.sort/is.sorted/ranges.is_sorted_until.pass.cpp b/libcxx/test/std/algorithms/alg.sorting/alg.sort/is.sorted/ranges.is_sorted_until.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.sorting/alg.sort/is.sorted/ranges.is_sorted_until.pass.cpp
@@ -0,0 +1,141 @@
+//===----------------------------------------------------------------------===//
+//
+// 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-has-no-incomplete-ranges
+
+// <algorithm>
+
+// template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
+//          indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
+//   constexpr I ranges::is_sorted_until(I first, S last, Comp comp = {}, Proj proj = {});
+// template<forward_range R, class Proj = identity,
+//          indirect_strict_weak_order<projected<iterator_t<R>, Proj>> Comp = ranges::less>
+//   constexpr borrowed_iterator_t<R>
+//     ranges::is_sorted_until(R&& r, Comp comp = {}, Proj proj = {});
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <concepts>
+#include <functional>
+#include <ranges>
+
+#include "test_iterators.h"
+
+template <class Iter, class Sent = Iter>
+constexpr void test_iterators() {
+  { // simple test
+    {
+      int a[] = {1, 2, 3, 4, 3};
+      std::same_as<Iter> auto ret = std::ranges::is_sorted_until(Iter(a), Sent(Iter(a + 5)));
+      assert(base(ret) == a + 4);
+    }
+    {
+      int a[] = {1, 2, 3, 4, 3};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+      std::same_as<Iter> auto ret = std::ranges::is_sorted_until(range);
+      assert(base(ret) == a + 4);
+    }
+  }
+
+  { // second element isn't sorted
+    {
+      int a[] = {1, 0, 3, 4, 3};
+      auto ret = std::ranges::is_sorted_until(Iter(a), Sent(Iter(a + 5)));
+      assert(base(ret) == a + 1);
+    }
+    {
+      int a[] = {1, 0, 3, 4, 3};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+      auto ret = std::ranges::is_sorted_until(range);
+      assert(base(ret) == a + 1);
+    }
+  }
+
+  { // all elements are sorted
+    {
+      int a[] = {1, 2, 3, 4, 5};
+      auto ret = std::ranges::is_sorted_until(Iter(a), Sent(Iter(a + 5)));
+      assert(base(ret) == a + 5);
+    }
+    {
+      int a[] = {1, 2, 3, 4, 5};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 5)));
+      auto ret = std::ranges::is_sorted_until(range);
+      assert(base(ret) == a + 5);
+    }
+  }
+
+  { // check that the comparator is used
+    {
+      int a[] = {5, 4, 3, 2};
+      auto ret = std::ranges::is_sorted_until(Iter(a), Sent(Iter(a + 4)), std::ranges::greater{});
+      assert(base(ret) == a + 4);
+    }
+    {
+      int a[] = {5, 4, 3, 2};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 4)));
+      auto ret = std::ranges::is_sorted_until(range, std::ranges::greater{});
+      assert(base(ret) == a + 4);
+    }
+  }
+
+  { // check that an empty range works
+    {
+      int a[] = {};
+      auto ret = std::ranges::is_sorted_until(Iter(a), Sent(Iter(a)));
+      assert(base(ret) == a);
+    }
+    {
+      int a[] = {};
+      auto range = std::ranges::subrange(Iter(a), Sent(Iter(a)));
+      auto ret = std::ranges::is_sorted_until(range);
+      assert(base(ret) == a);
+    }
+  }
+}
+
+constexpr bool test() {
+  test_iterators<forward_iterator<int*>>();
+  test_iterators<bidirectional_iterator<int*>>();
+  test_iterators<random_access_iterator<int*>>();
+  test_iterators<contiguous_iterator<int*>>();
+  test_iterators<int*>();
+  test_iterators<const int*>();
+
+  { // check that the comparator is used
+    struct S {
+      int i;
+      constexpr S(int i_) : i(i_) {}
+    };
+    {
+      S a[] = {1, 2, 3};
+      auto ret = std::ranges::is_sorted_until(a, a + 3, {}, &S::i);
+      assert(base(ret) == a + 3);
+    }
+    {
+      S a[] = {1, 2, 3};
+      auto ret = std::ranges::is_sorted_until(a, {}, &S::i);
+      assert(base(ret) == a + 3);
+    }
+  }
+
+  { // check that std::ranges::dangling is returned
+    [[maybe_unused]] std::same_as<std::ranges::dangling> auto ret = std::ranges::is_sorted_until(std::array{1, 2, 3});
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}