diff --git a/libcxx/docs/OneRangesProposalStatus.csv b/libcxx/docs/OneRangesProposalStatus.csv
--- a/libcxx/docs/OneRangesProposalStatus.csv
+++ b/libcxx/docs/OneRangesProposalStatus.csv
@@ -3,7 +3,7 @@
 [tuple.helper],Update <tuple> includes.,,,,
 [function.objects],"Comparison functions: equal_to, less, etc.",[concepts],Zoe Carver,D100429,
 [memory.syn],Add specializations for uninitialized_* and destroy_*. ,"[concepts], [readable.traits]: iter_value_t",,,
-[readable.traits]: indirectly_readable_traits,indirectly_readable_traits only. ,[concepts],Christopher Di Bella,D99461,
+[readable.traits]: indirectly_readable_traits,indirectly_readable_traits only. ,[concepts],Christopher Di Bella,D99461,✅
 [iterator.traits],Mainly updates to iterator_traits.,"[readable.traits]: indirectly_readable_traits, [concepts]",Christopher Di Bella,"D99854, D99855",
 [readable.traits]: iter_value_t,Finish implementing readable.traits.,"[readable.traits]: indirectly_readable_traits, [concepts], [iterator.traits]",Christopher Di Bella,D99863,
 [specialized.algorithms],NOT FINISHED,NOT FINISHED,,,
@@ -58,4 +58,4 @@
 [range.split],split_view,[range.all],,,
 [range.counted],view::counted,[range.subrange],,,
 [range.common],common_view,[range.all],,,
-[range.reverse],reverse_view,[range.all],,,
\ No newline at end of file
+[range.reverse],reverse_view,[range.all],,,
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -48,6 +48,11 @@
 using iter_rvalue_reference_t
   = decltype(ranges::iter_move(declval<T&>()));
 
+// [iterator.concepts], iterator concepts
+// [iterator.concept.readable], concept indirectly_­readable
+template<class In>
+  concept indirectly_readable = see below;                // since C++20
+
 template<class Category, class T, class Distance = ptrdiff_t,
          class Pointer = T*, class Reference = T&>
 struct iterator
@@ -2513,6 +2518,23 @@
 requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __referenceable; }
 using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<_Tp&>()));
 
+// [iterator.concept.readable]
+template<class _In>
+concept __indirectly_readable_impl =
+  requires(const _In __in) {
+    typename iter_value_t<_In>;
+    typename iter_reference_t<_In>;
+    typename iter_rvalue_reference_t<_In>;
+    { *__in } -> same_as<iter_reference_t<_In>>;
+    { ranges::iter_move(__in) } -> same_as<iter_rvalue_reference_t<_In>>;
+  } &&
+  common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> &&
+  common_reference_with<iter_reference_t<_In>&&, iter_rvalue_reference_t<_In>&&> &&
+  common_reference_with<iter_rvalue_reference_t<_In>&&, const iter_value_t<_In>&>;
+
+template<class _In>
+concept indirectly_readable = __indirectly_readable_impl<remove_cvref_t<_In>>;
+
 #undef _LIBCPP_NOEXCEPT_RETURN
 #endif // !defined(_LIBCPP_HAS_NO_RANGES)
 
diff --git a/libcxx/test/std/containers/associative/map/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/map/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/associative/map/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <map>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::map<int, int>::iterator>);
+static_assert(std::indirectly_readable<std::map<int, int>::const_iterator>);
+static_assert(std::indirectly_readable<std::map<int, int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::map<int, int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/associative/multimap/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/multimap/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/associative/multimap/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <map>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::multimap<int, int>::iterator>);
+static_assert(std::indirectly_readable<std::multimap<int, int>::const_iterator>);
+static_assert(std::indirectly_readable<std::multimap<int, int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::multimap<int, int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/associative/multiset/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/multiset/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/associative/multiset/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <set>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::multiset<int>::iterator>);
+static_assert(std::indirectly_readable<std::multiset<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::multiset<int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::multiset<int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/associative/set/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/set/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/associative/set/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <set>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::set<int>::iterator>);
+static_assert(std::indirectly_readable<std::set<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::set<int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::set<int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/sequences/array/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/array/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/sequences/array/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <array>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::array<int, 10>::iterator>);
+static_assert(std::indirectly_readable<std::array<int, 10>::const_iterator>);
+static_assert(std::indirectly_readable<std::array<int, 10>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::array<int, 10>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/sequences/deque/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/deque/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/sequences/deque/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <deque>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::deque<int>::iterator>);
+static_assert(std::indirectly_readable<std::deque<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::deque<int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::deque<int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.iter/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.iter/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.iter/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator
+
+#include <forward_list>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::forward_list<int>::iterator>);
+static_assert(std::indirectly_readable<std::forward_list<int>::const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/list/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/list/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/sequences/list/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <list>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::list<int>::iterator>);
+static_assert(std::indirectly_readable<std::list<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::list<int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::list<int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/sequences/vector/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/vector/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/sequences/vector/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <vector>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::vector<int>::iterator>);
+static_assert(std::indirectly_readable<std::vector<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::vector<int>::reverse_iterator>);
+static_assert(std::indirectly_readable<std::vector<int>::const_reverse_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.map/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.map/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.map/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, local_iterator, const_local_iterator
+
+#include <unordered_map>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::unordered_map<int, int>::iterator>);
+static_assert(std::indirectly_readable<std::unordered_map<int, int>::const_iterator>);
+static_assert(std::indirectly_readable<std::unordered_map<int, int>::local_iterator>);
+static_assert(std::indirectly_readable<std::unordered_map<int, int>::const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.multimap/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.multimap/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.multimap/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, local_iterator, const_local_iterator
+
+#include <unordered_map>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::unordered_multimap<int, int>::iterator>);
+static_assert(std::indirectly_readable<std::unordered_multimap<int, int>::const_iterator>);
+static_assert(std::indirectly_readable<std::unordered_multimap<int, int>::local_iterator>);
+static_assert(std::indirectly_readable<std::unordered_multimap<int, int>::const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.multiset/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.multiset/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.multiset/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, local_iterator, const_local_iterator
+
+#include <unordered_set>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::unordered_multiset<int>::iterator>);
+static_assert(std::indirectly_readable<std::unordered_multiset<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::unordered_multiset<int>::local_iterator>);
+static_assert(std::indirectly_readable<std::unordered_multiset<int>::const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.set/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.set/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.set/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, local_iterator, const_local_iterator
+
+#include <unordered_set>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::unordered_set<int>::iterator>);
+static_assert(std::indirectly_readable<std::unordered_set<int>::const_iterator>);
+static_assert(std::indirectly_readable<std::unordered_set<int>::local_iterator>);
+static_assert(std::indirectly_readable<std::unordered_set<int>::const_local_iterator>);
diff --git a/libcxx/test/std/containers/views/span.iterators/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/views/span.iterators/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/views/span.iterators/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, reverse_iterator
+
+#include <span>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::span<int>::iterator>);
+static_assert(std::indirectly_readable<std::span<int>::reverse_iterator>);
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/input.output/filesystems/class.directory_iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// directory_iterator, recursive_directory_iterator
+
+#include "filesystem_include.h"
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<fs::directory_iterator>);
+static_assert(std::indirectly_readable<fs::recursive_directory_iterator>);
diff --git a/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.readable/indirectly_readable.compile.pass.cpp b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.readable/indirectly_readable.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.readable/indirectly_readable.compile.pass.cpp
@@ -0,0 +1,176 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 In>
+// concept indirectly_readable;
+
+#include <iterator>
+
+#include <concepts>
+#include <optional>
+
+#include "read_write.h"
+
+template <class In>
+[[nodiscard]] constexpr bool check_indirectly_readable() {
+  constexpr bool result = std::indirectly_readable<In>;
+  static_assert(std::indirectly_readable<In const> == result);
+  static_assert(std::indirectly_readable<In volatile> == result);
+  static_assert(std::indirectly_readable<In const volatile> == result);
+  static_assert(std::indirectly_readable<In const&> == result);
+  static_assert(std::indirectly_readable<In volatile&> == result);
+  static_assert(std::indirectly_readable<In const volatile&> == result);
+  static_assert(std::indirectly_readable<In const&&> == result);
+  static_assert(std::indirectly_readable<In volatile&&> == result);
+  static_assert(std::indirectly_readable<In const volatile&&> == result);
+  return result;
+}
+
+static_assert(check_indirectly_readable<value_type_indirection>());
+static_assert(check_indirectly_readable<element_type_indirection>());
+static_assert(check_indirectly_readable<proxy_indirection>());
+static_assert(check_indirectly_readable<read_only_indirection>());
+
+struct indirection_mismatch {
+  using value_type = int;
+  float& operator*() const;
+};
+static_assert(!std::same_as<std::iter_value_t<indirection_mismatch>, std::iter_reference_t<indirection_mismatch> > &&
+              check_indirectly_readable<indirection_mismatch>());
+static_assert(!check_indirectly_readable<missing_dereference>());
+
+// `iter_rvalue_reference_t` can't be missing unless the dereference operator is also missing.
+
+struct iter_move_mismatch {
+  using value_type = int;
+  value_type& operator*() const;
+
+  friend float& iter_move(iter_move_mismatch&);
+};
+static_assert(!check_indirectly_readable<iter_move_mismatch>());
+
+struct indirection_and_iter_move_mismatch {
+  using value_type = int;
+  float& operator*() const;
+
+  friend unsigned long long& iter_move(indirection_and_iter_move_mismatch&);
+};
+static_assert(!check_indirectly_readable<indirection_and_iter_move_mismatch>());
+
+struct missing_iter_value_t {
+  int operator*() const;
+};
+static_assert(!check_indirectly_readable<missing_iter_value_t>());
+
+struct unrelated_lvalue_ref_and_rvalue_ref {};
+
+struct iter_ref1 {};
+namespace std {
+template <>
+struct common_reference<iter_ref1&, iter_ref1&&> {};
+
+template <>
+struct common_reference<iter_ref1&&, iter_ref1&> {};
+} // namespace std
+static_assert(!std::common_reference_with<iter_ref1&, iter_ref1&&>);
+
+struct bad_iter_reference_t {
+  using value_type = int;
+  iter_ref1& operator*() const;
+};
+static_assert(!check_indirectly_readable<bad_iter_reference_t>());
+
+struct iter_ref2 {};
+struct iter_rvalue_ref {};
+
+struct unrelated_iter_ref_rvalue_and_iter_rvalue_ref_rvalue {
+  using value_type = iter_ref2;
+  iter_ref2& operator*() const;
+  friend iter_rvalue_ref&& iter_move(unrelated_iter_ref_rvalue_and_iter_rvalue_ref_rvalue);
+};
+static_assert(!check_indirectly_readable<unrelated_iter_ref_rvalue_and_iter_rvalue_ref_rvalue>());
+
+struct iter_ref3 {
+  operator iter_rvalue_ref() const;
+};
+namespace std {
+template <template <class> class XQual, template <class> class YQual>
+struct basic_common_reference<iter_ref3, iter_rvalue_ref, XQual, YQual> {
+  using type = iter_rvalue_ref;
+};
+template <template <class> class XQual, template <class> class YQual>
+struct basic_common_reference<iter_rvalue_ref, iter_ref3, XQual, YQual> {
+  using type = iter_rvalue_ref;
+};
+} // namespace std
+static_assert(std::common_reference_with<iter_ref3&&, iter_rvalue_ref&&>);
+
+struct different_reference_types_with_common_reference {
+  using value_type = iter_ref3;
+  iter_ref3& operator*() const;
+  friend iter_rvalue_ref&& iter_move(different_reference_types_with_common_reference);
+};
+static_assert(check_indirectly_readable<different_reference_types_with_common_reference>());
+
+struct iter_ref4 {
+  operator iter_rvalue_ref() const;
+};
+namespace std {
+template <template <class> class XQual, template <class> class YQual>
+struct basic_common_reference<iter_ref4, iter_rvalue_ref, XQual, YQual> {
+  using type = iter_rvalue_ref;
+};
+template <template <class> class XQual, template <class> class YQual>
+struct basic_common_reference<iter_rvalue_ref, iter_ref4, XQual, YQual> {
+  using type = iter_rvalue_ref;
+};
+
+template <>
+struct common_reference<iter_ref4 const&, iter_rvalue_ref&&> {};
+template <>
+struct common_reference<iter_rvalue_ref&&, iter_ref4 const&> {};
+} // namespace std
+static_assert(std::common_reference_with<iter_ref4&&, iter_rvalue_ref&&>);
+static_assert(!std::common_reference_with<iter_ref4 const&, iter_rvalue_ref&&>);
+
+struct different_reference_types_without_common_reference_to_const {
+  using value_type = iter_ref4;
+  iter_ref4& operator*() const;
+  friend iter_rvalue_ref&& iter_move(different_reference_types_without_common_reference_to_const);
+};
+static_assert(!check_indirectly_readable<different_reference_types_without_common_reference_to_const>());
+
+struct non_const_deref {
+  int& operator*();
+};
+static_assert(!check_indirectly_readable<non_const_deref>());
+
+namespace standard_types {
+static_assert(!check_indirectly_readable<void*>());
+static_assert(!check_indirectly_readable<void const*>());
+static_assert(!check_indirectly_readable<void volatile*>());
+static_assert(!check_indirectly_readable<void const volatile*>());
+
+static_assert(check_indirectly_readable<int*>());
+static_assert(check_indirectly_readable<int const*>());
+static_assert(check_indirectly_readable<int volatile*>());
+static_assert(check_indirectly_readable<int const volatile*>());
+
+// <memory>
+static_assert(check_indirectly_readable<std::shared_ptr<int> >());
+static_assert(!check_indirectly_readable<std::shared_ptr<void> >());
+static_assert(check_indirectly_readable<std::unique_ptr<int> >());
+static_assert(!check_indirectly_readable<std::unique_ptr<void> >());
+
+// <optional>
+static_assert(!check_indirectly_readable<std::optional<int> >());
+} // namespace standard_types
diff --git a/libcxx/test/std/iterators/predef.iterators/insert.iterators/back.insert.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/predef.iterators/insert.iterators/back.insert.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/insert.iterators/back.insert.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// back_insert_iterator
+
+#include <iterator>
+
+#include <vector>
+
+static_assert(!std::indirectly_readable<std::back_insert_iterator<std::vector<int> > >);
diff --git a/libcxx/test/std/iterators/predef.iterators/insert.iterators/front.insert.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/predef.iterators/insert.iterators/front.insert.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/insert.iterators/front.insert.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// front_insert_iterator
+
+#include <iterator>
+
+#include <list>
+
+static_assert(!std::indirectly_readable<std::front_insert_iterator<std::list<int> > >);
diff --git a/libcxx/test/std/iterators/predef.iterators/insert.iterators/insert.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/predef.iterators/insert.iterators/insert.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/insert.iterators/insert.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// insert_iterator
+
+#include <iterator>
+
+#include <vector>
+
+static_assert(!std::indirectly_readable<std::insert_iterator<std::vector<int> > >);
diff --git a/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// move_iterator
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::move_iterator<int*> >);
diff --git a/libcxx/test/std/iterators/stream.iterators/istream.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/stream.iterators/istream.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/stream.iterators/istream.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// istream_iterator
+
+#include <iterator>
+
+#include <iosfwd>
+
+static_assert(std::indirectly_readable<std::istream_iterator<int, std::istream> >);
diff --git a/libcxx/test/std/iterators/stream.iterators/istreambuf.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/stream.iterators/istreambuf.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/stream.iterators/istreambuf.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// istreambuf_iterator
+
+#include <iterator>
+
+#include <istream>
+#include <string>
+
+static_assert(std::indirectly_readable<std::istreambuf_iterator<char> >);
diff --git a/libcxx/test/std/iterators/stream.iterators/ostream.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/stream.iterators/ostream.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/stream.iterators/ostream.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// ostream_iterator
+
+#include <iterator>
+
+#include <iosfwd>
+
+static_assert(!std::indirectly_readable<std::ostream_iterator<int, std::ostream> >);
diff --git a/libcxx/test/std/iterators/stream.iterators/ostreambuf.iterator/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/stream.iterators/ostreambuf.iterator/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/stream.iterators/ostreambuf.iterator/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// ostreambuf_iterator
+
+#include <iterator>
+
+#include <ostream>
+#include <string>
+
+static_assert(!std::indirectly_readable<std::ostreambuf_iterator<char> >);
diff --git a/libcxx/test/std/re/re.iter/re.regiter/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/re/re.iter/re.regiter/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/re/re.iter/re.regiter/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// regex_iterator
+
+#include <regex>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::regex_iterator<std::string_view::iterator> >);
+static_assert(std::indirectly_readable<std::regex_iterator<std::string_view::const_iterator> >);
+static_assert(std::indirectly_readable<std::regex_iterator<std::string_view::reverse_iterator> >);
+static_assert(std::indirectly_readable<std::regex_iterator<std::string_view::const_reverse_iterator> >);
diff --git a/libcxx/test/std/re/re.iter/re.tokiter/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/re/re.iter/re.tokiter/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/re/re.iter/re.tokiter/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// regex_token_iterator
+
+#include <regex>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::regex_token_iterator<std::string_view::iterator> >);
+static_assert(std::indirectly_readable<std::regex_token_iterator<std::string_view::const_iterator> >);
+static_assert(std::indirectly_readable<std::regex_token_iterator<std::string_view::reverse_iterator> >);
+static_assert(std::indirectly_readable<std::regex_token_iterator<std::string_view::const_reverse_iterator> >);
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <string>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::string::iterator>);
+static_assert(std::indirectly_readable<std::string::const_iterator>);
+static_assert(std::indirectly_readable<std::string::reverse_iterator>);
+static_assert(std::indirectly_readable<std::string::const_reverse_iterator>);
diff --git a/libcxx/test/std/strings/string.view/string.view.iterators/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/strings/string.view/string.view.iterators/iterator_concept_conformance.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.iterators/iterator_concept_conformance.compile.pass.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// iterator, const_iterator, reverse_iterator, const_reverse_iterator
+
+#include <string_view>
+
+#include <iterator>
+
+static_assert(std::indirectly_readable<std::string_view::iterator>);
+static_assert(std::indirectly_readable<std::string_view::const_iterator>);
+static_assert(std::indirectly_readable<std::string_view::reverse_iterator>);
+static_assert(std::indirectly_readable<std::string_view::const_reverse_iterator>);
diff --git a/libcxx/test/support/read_write.h b/libcxx/test/support/read_write.h
new file mode 100644
--- /dev/null
+++ b/libcxx/test/support/read_write.h
@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TEST_SUPPORT_READ_WRITE_H
+#define LIBCPP_TEST_SUPPORT_READ_WRITE_H
+
+struct value_type_indirection {
+  using value_type = int;
+  value_type& operator*() const;
+};
+
+struct element_type_indirection {
+  using element_type = long;
+  element_type& operator*() const;
+};
+
+struct proxy_indirection {
+  using value_type = int;
+  value_type operator*() const;
+};
+
+struct read_only_indirection {
+  using value_type = int const;
+  value_type& operator*() const;
+};
+
+// doubles as missing_iter_reference_t
+struct missing_dereference {
+  using value_type = int;
+};
+
+#endif // LIBCPP_TEST_SUPPORT_READ_WRITE_H