diff --git a/libcxx/include/__iterator/concepts.h b/libcxx/include/__iterator/concepts.h
--- a/libcxx/include/__iterator/concepts.h
+++ b/libcxx/include/__iterator/concepts.h
@@ -99,6 +99,14 @@
   input_or_output_iterator<_Ip> &&
   __weakly_equality_comparable_with<_Sp, _Ip>;
 
+// [iterator.concept.input]
+template<class _Ip>
+concept input_iterator =
+  input_or_output_iterator<_Ip> &&
+  indirectly_readable<_Ip> &&
+  requires { typename _ITER_CONCEPT<_Ip>; } &&
+  derived_from<_ITER_CONCEPT<_Ip>, input_iterator_tag>;
+
 // clang-format on
 
 #endif // !defined(_LIBCPP_HAS_NO_RANGES)
diff --git a/libcxx/include/__ranges/concepts.h b/libcxx/include/__ranges/concepts.h
--- a/libcxx/include/__ranges/concepts.h
+++ b/libcxx/include/__ranges/concepts.h
@@ -10,6 +10,7 @@
 #define _LIBCPP_RANGES_CONCEPTS_H
 
 #include <__config>
+#include <__iterator/concepts.h>
 #include <__ranges/begin.h>
 #include <__ranges/end.h>
 #include <type_traits>
@@ -53,6 +54,9 @@
   using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<_Rp> >;
 
   // [range.refinements], other range refinements
+  template <class _Tp>
+  concept input_range = range<_Tp> && input_iterator<iterator_t<_Tp> >;
+
   template <class _Tp>
   concept common_range = range<_Tp> && same_as<iterator_t<_Tp>, sentinel_t<_Tp> >;
 } // namespace ranges
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -68,6 +68,10 @@
 template<class S, class I>
   concept sentinel_for = see below;                        // since C++20
 
+// [iterator.concept.input], concept input_­iterator
+template<class I>
+  concept input_iterator = see below;                      // since C++20
+
 template<class Category, class T, class Distance = ptrdiff_t,
          class Pointer = T*, class Reference = T&>
 struct iterator
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -48,6 +48,9 @@
     using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<R>>;
 
   // [range.refinements], other range refinements
+  template<class T>
+    concept input_range = see below;
+
   template <class _Tp>
     concept common_range = see below;
 }
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/associative/map/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/map/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/associative/map/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/associative/map/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/associative/multimap/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/multimap/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/associative/multimap/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/associative/multimap/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -38,3 +39,4 @@
 static_assert(std::sentinel_for<const_iterator, iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/associative/set/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/associative/set/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/associative/set/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/associative/set/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range>);
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
--- 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
@@ -30,6 +30,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, int>);
@@ -39,3 +40,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/array/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/array/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/array/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/array/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/deque/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/deque/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/deque/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/deque/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -27,6 +27,7 @@
 static_assert(std::input_or_output_iterator<iterator>);
 static_assert(std::sentinel_for<iterator, iterator>);
 static_assert(std::sentinel_for<iterator, const_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -34,3 +35,4 @@
 static_assert(std::input_or_output_iterator<const_iterator>);
 static_assert(std::sentinel_for<const_iterator, iterator>);
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/forwardlist/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/forwardlist/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/forwardlist/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/forwardlist/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/list/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/list/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/list/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/list/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
diff --git a/libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/vector.bool/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/vector.bool/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/vector.bool/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/vector.bool/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,3 +41,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/containers/sequences/vector/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/sequences/vector/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/sequences/vector/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/sequences/vector/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, local_iterator>);
 static_assert(!std::sentinel_for<iterator, const_local_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -38,6 +39,7 @@
 static_assert(std::sentinel_for<const_iterator, iterator>);
 static_assert(!std::sentinel_for<const_iterator, local_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_iterator>);
 
 static_assert(std::indirectly_readable<local_iterator>);
 static_assert(std::incrementable<local_iterator>);
@@ -46,6 +48,7 @@
 static_assert(!std::sentinel_for<local_iterator, const_iterator>);
 static_assert(std::sentinel_for<local_iterator, local_iterator>);
 static_assert(std::sentinel_for<local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<local_iterator>);
 
 static_assert(std::indirectly_readable<const_local_iterator>);
 static_assert(!std::indirectly_writable<const_local_iterator, value_type>);
@@ -55,3 +58,4 @@
 static_assert(!std::sentinel_for<const_local_iterator, const_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, local_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.map/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.map/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/unord/unord.map/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.map/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, local_iterator>);
 static_assert(!std::sentinel_for<iterator, const_local_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,6 +41,7 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, local_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_iterator>);
 
 static_assert(std::indirectly_readable<local_iterator>);
 static_assert(!std::indirectly_writable<local_iterator, value_type>);
@@ -49,6 +51,7 @@
 static_assert(!std::sentinel_for<local_iterator, const_iterator>);
 static_assert(std::sentinel_for<local_iterator, local_iterator>);
 static_assert(std::sentinel_for<local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<local_iterator>);
 
 static_assert(std::indirectly_readable<const_local_iterator>);
 static_assert(!std::indirectly_writable<const_local_iterator, value_type>);
@@ -58,3 +61,4 @@
 static_assert(!std::sentinel_for<const_local_iterator, const_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, local_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.multimap/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.multimap/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/unord/unord.multimap/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.multimap/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, local_iterator>);
 static_assert(!std::sentinel_for<iterator, const_local_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -40,6 +41,7 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, local_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_iterator>);
 
 static_assert(std::indirectly_readable<local_iterator>);
 static_assert(!std::indirectly_writable<local_iterator, value_type>);
@@ -49,6 +51,7 @@
 static_assert(!std::sentinel_for<local_iterator, const_iterator>);
 static_assert(std::sentinel_for<local_iterator, local_iterator>);
 static_assert(std::sentinel_for<local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<local_iterator>);
 
 static_assert(std::indirectly_readable<const_local_iterator>);
 static_assert(!std::indirectly_writable<const_local_iterator, value_type>);
@@ -58,3 +61,4 @@
 static_assert(!std::sentinel_for<const_local_iterator, const_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, local_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.multiset/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.multiset/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/unord/unord.multiset/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.multiset/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, local_iterator>);
 static_assert(!std::sentinel_for<iterator, const_local_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -38,6 +39,7 @@
 static_assert(std::sentinel_for<const_iterator, iterator>);
 static_assert(!std::sentinel_for<const_iterator, local_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_iterator>);
 
 static_assert(std::indirectly_readable<local_iterator>);
 static_assert(std::incrementable<local_iterator>);
@@ -46,6 +48,7 @@
 static_assert(!std::sentinel_for<local_iterator, const_iterator>);
 static_assert(std::sentinel_for<local_iterator, local_iterator>);
 static_assert(std::sentinel_for<local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<local_iterator>);
 
 static_assert(std::indirectly_readable<const_local_iterator>);
 static_assert(!std::indirectly_writable<const_local_iterator, value_type>);
@@ -55,3 +58,4 @@
 static_assert(!std::sentinel_for<const_local_iterator, const_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, local_iterator>);
 static_assert(std::sentinel_for<const_local_iterator, const_local_iterator>);
+static_assert(std::input_iterator<const_local_iterator>);
diff --git a/libcxx/test/std/containers/unord/unord.set/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/unord/unord.set/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/unord/unord.set/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.set/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
diff --git a/libcxx/test/std/containers/views/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/containers/views/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/containers/views/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/containers/views/range_concept_conformance.compile.pass.cpp
@@ -23,6 +23,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
+static_assert(stdr::input_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::iterator>);
 static_assert(stdr::common_range<range const>);
+static_assert(stdr::input_range<range const>);
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
--- 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
@@ -27,3 +27,4 @@
 static_assert(std::input_or_output_iterator<iterator>);
 static_assert(std::sentinel_for<iterator, iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
+static_assert(std::input_iterator<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
--- 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
@@ -23,6 +23,7 @@
 static_assert(!std::incrementable<fs::directory_iterator>);
 static_assert(std::input_or_output_iterator<fs::directory_iterator>);
 static_assert(std::sentinel_for<fs::directory_iterator, fs::directory_iterator>);
+static_assert(std::input_iterator<fs::directory_iterator>);
 
 static_assert(std::indirectly_readable<fs::recursive_directory_iterator>);
 static_assert(
@@ -31,3 +32,4 @@
 static_assert(!std::incrementable<fs::recursive_directory_iterator>);
 static_assert(std::input_or_output_iterator<fs::recursive_directory_iterator>);
 static_assert(std::sentinel_for<fs::recursive_directory_iterator, fs::recursive_directory_iterator>);
+static_assert(std::input_iterator<fs::recursive_directory_iterator>);
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_iterator/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_iterator/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/input.output/filesystems/class.directory_iterator/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_iterator/range_concept_conformance.compile.pass.cpp
@@ -22,12 +22,16 @@
 
 static_assert(std::same_as<stdr::iterator_t<fs::directory_iterator>, fs::directory_iterator>);
 static_assert(stdr::common_range<fs::directory_iterator>);
+static_assert(stdr::input_range<fs::directory_iterator>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::directory_iterator const>, fs::directory_iterator>);
 static_assert(stdr::common_range<fs::directory_iterator const>);
+static_assert(stdr::input_range<fs::directory_iterator const>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::recursive_directory_iterator>, fs::recursive_directory_iterator>);
 static_assert(stdr::common_range<fs::recursive_directory_iterator>);
+static_assert(stdr::input_range<fs::directory_iterator>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::recursive_directory_iterator const>, fs::recursive_directory_iterator>);
 static_assert(stdr::common_range<fs::recursive_directory_iterator const>);
+static_assert(stdr::input_range<fs::directory_iterator const>);
diff --git a/libcxx/test/std/input.output/filesystems/class.path/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/input.output/filesystems/class.path/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/range_concept_conformance.compile.pass.cpp
@@ -22,6 +22,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<fs::path>, fs::path::iterator>);
 static_assert(stdr::common_range<fs::path>);
+static_assert(stdr::input_range<fs::path>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::path const>, fs::path::const_iterator>);
 static_assert(stdr::common_range<fs::path const>);
+static_assert(stdr::input_range<fs::path const>);
diff --git a/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp
@@ -0,0 +1,125 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// XFAIL: msvc && clang
+
+// template<class T>
+// concept input_iterator;
+
+#include <iterator>
+
+#include "test_iterators.h"
+
+static_assert(std::input_iterator<input_iterator<int*> >);
+static_assert(std::input_iterator<cxx20_input_iterator<int*> >);
+
+struct no_explicit_iter_concept {
+  using value_type = int;
+  using difference_type = std::ptrdiff_t;
+
+  no_explicit_iter_concept() = default;
+
+  no_explicit_iter_concept(no_explicit_iter_concept&&) = default;
+  no_explicit_iter_concept& operator=(no_explicit_iter_concept&&) = default;
+
+  no_explicit_iter_concept(no_explicit_iter_concept const&) = delete;
+  no_explicit_iter_concept& operator=(no_explicit_iter_concept const&) = delete;
+
+  value_type operator*() const;
+
+  no_explicit_iter_concept& operator++();
+  void operator++(int);
+};
+// ITER-CONCEPT is `random_access_iterator_tag` >:(
+static_assert(std::input_iterator<no_explicit_iter_concept>);
+
+static_assert(std::input_iterator<int*>);
+static_assert(std::input_iterator<int const*>);
+static_assert(std::input_iterator<int volatile*>);
+static_assert(std::input_iterator<int const volatile*>);
+
+struct not_weakly_incrementable {
+  using difference_type = std::ptrdiff_t;
+  using iterator_concept = std::input_iterator_tag;
+
+  not_weakly_incrementable() = default;
+
+  not_weakly_incrementable(not_weakly_incrementable&&) = default;
+  not_weakly_incrementable& operator=(not_weakly_incrementable&&) = default;
+
+  not_weakly_incrementable(not_weakly_incrementable const&) = delete;
+  not_weakly_incrementable& operator=(not_weakly_incrementable const&) = delete;
+
+  int operator*() const;
+
+  not_weakly_incrementable& operator++();
+};
+static_assert(!std::input_or_output_iterator<not_weakly_incrementable> &&
+              !std::input_iterator<not_weakly_incrementable>);
+
+struct not_indirectly_readable {
+  using difference_type = std::ptrdiff_t;
+  using iterator_concept = std::input_iterator_tag;
+
+  not_indirectly_readable() = default;
+
+  not_indirectly_readable(not_indirectly_readable&&) = default;
+  not_indirectly_readable& operator=(not_indirectly_readable&&) = default;
+
+  not_indirectly_readable(not_indirectly_readable const&) = delete;
+  not_indirectly_readable& operator=(not_indirectly_readable const&) = delete;
+
+  int operator*() const;
+
+  not_indirectly_readable& operator++();
+  void operator++(int);
+};
+static_assert(!std::indirectly_readable<not_indirectly_readable> && !std::input_iterator<not_indirectly_readable>);
+
+struct bad_iterator_category {
+  using value_type = int;
+  using difference_type = std::ptrdiff_t;
+  using iterator_category = void;
+
+  bad_iterator_category() = default;
+
+  bad_iterator_category(bad_iterator_category&&) = default;
+  bad_iterator_category& operator=(bad_iterator_category&&) = default;
+
+  bad_iterator_category(bad_iterator_category const&) = delete;
+  bad_iterator_category& operator=(bad_iterator_category const&) = delete;
+
+  value_type operator*() const;
+
+  bad_iterator_category& operator++();
+  void operator++(int);
+};
+static_assert(!std::input_iterator<bad_iterator_category>);
+
+struct bad_iterator_concept {
+  using value_type = int;
+  using difference_type = std::ptrdiff_t;
+  using iterator_concept = void*;
+
+  bad_iterator_concept() = default;
+
+  bad_iterator_concept(bad_iterator_concept&&) = default;
+  bad_iterator_concept& operator=(bad_iterator_concept&&) = default;
+
+  bad_iterator_concept(bad_iterator_concept const&) = delete;
+  bad_iterator_concept& operator=(bad_iterator_concept const&) = delete;
+
+  value_type operator*() const;
+
+  bad_iterator_concept& operator++();
+  void operator++(int);
+};
+static_assert(!std::input_iterator<bad_iterator_concept>);
diff --git a/libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/subsumption.compile.pass.cpp
copy from libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp
copy to libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/subsumption.compile.pass.cpp
--- a/libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/subsumption.compile.pass.cpp
@@ -11,18 +11,25 @@
 // UNSUPPORTED: gcc-10
 // XFAIL: msvc && clang
 
-// multiset
+// template<class T>
+// concept input_iterator;
 
-#include <set>
+#include <iterator>
 
 #include <concepts>
-#include <ranges>
 
-using range = std::multiset<int>;
-namespace stdr = std::ranges;
+// clang-format off
+template<std::input_or_output_iterator I>
+requires std::indirectly_readable<I> &&
+         std::derived_from<std::_ITER_CONCEPT<I>, std::input_iterator_tag>
+[[nodiscard]] constexpr bool check_subsumption() {
+  return false;
+}
 
-static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
-static_assert(stdr::common_range<range>);
+template<std::input_iterator>
+[[nodiscard]] constexpr bool check_subsumption() {
+  return true;
+}
+// clang-format on
 
-static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
-static_assert(stdr::common_range<range const>);
+static_assert(check_subsumption<int*>());
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
--- 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
@@ -23,3 +23,4 @@
 static_assert(!std::weakly_incrementable<iterator>);
 static_assert(!std::input_or_output_iterator<iterator>);
 static_assert(!std::sentinel_for<iterator, iterator>);
+static_assert(!std::input_iterator<iterator>);
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
--- 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
@@ -23,3 +23,4 @@
 static_assert(!std::weakly_incrementable<iterator>);
 static_assert(!std::input_or_output_iterator<iterator>);
 static_assert(!std::sentinel_for<iterator, iterator>);
+static_assert(!std::input_iterator<iterator>);
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
--- 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
@@ -23,3 +23,4 @@
 static_assert(!std::weakly_incrementable<iterator>);
 static_assert(!std::input_or_output_iterator<iterator>);
 static_assert(!std::sentinel_for<iterator, iterator>);
+static_assert(!std::input_iterator<iterator>);
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
--- 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
@@ -21,3 +21,4 @@
 static_assert(std::incrementable<iterator>);
 static_assert(std::input_or_output_iterator<iterator>);
 static_assert(std::sentinel_for<iterator, iterator>);
+static_assert(std::input_iterator<iterator>);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp
@@ -22,6 +22,7 @@
 static_assert(std::incrementable<iterator>);
 static_assert(std::input_or_output_iterator<iterator>);
 static_assert(std::sentinel_for<iterator, iterator>);
+static_assert(std::input_iterator<iterator>);
 
 using other_iterator = std::reverse_iterator<float*>;
 static_assert(std::sentinel_for<iterator, other_iterator>);
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
--- 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
@@ -23,3 +23,4 @@
 static_assert(std::incrementable<iterator>);
 static_assert(std::input_or_output_iterator<iterator>);
 static_assert(std::sentinel_for<iterator, iterator>);
+static_assert(std::input_iterator<iterator>);
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
--- 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
@@ -25,3 +25,4 @@
 static_assert(!std::incrementable<iterator>);
 static_assert(std::input_or_output_iterator<iterator>);
 static_assert(std::sentinel_for<iterator, iterator>);
+static_assert(std::input_iterator<iterator>);
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
--- 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
@@ -23,3 +23,4 @@
 static_assert(!std::weakly_incrementable<iterator>);
 static_assert(!std::input_or_output_iterator<iterator>);
 static_assert(!std::sentinel_for<iterator, iterator>);
+static_assert(!std::input_iterator<iterator>);
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
--- 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
@@ -24,3 +24,4 @@
 static_assert(!std::weakly_incrementable<iterator>);
 static_assert(!std::input_or_output_iterator<iterator>);
 static_assert(!std::sentinel_for<iterator, iterator>);
+static_assert(!std::input_iterator<iterator>);
diff --git a/libcxx/test/std/ranges/range.refinements/input_range.compile.pass.cpp b/libcxx/test/std/ranges/range.refinements/input_range.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/ranges/range.refinements/input_range.compile.pass.cpp
@@ -0,0 +1,45 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// XFAIL: msvc && clang
+
+// template<range _Rp>
+// concept input_range;
+
+#include <ranges>
+
+#include "test_range.h"
+
+namespace stdr = std::ranges;
+
+static_assert(stdr::input_range<test_range<input_iterator> >);
+static_assert(stdr::input_range<test_range<input_iterator> const>);
+
+static_assert(stdr::input_range<test_range<cxx20_input_iterator> >);
+static_assert(stdr::input_range<test_range<cxx20_input_iterator> const>);
+
+static_assert(stdr::input_range<test_non_const_range<input_iterator> >);
+static_assert(stdr::input_range<test_non_const_range<cxx20_input_iterator> >);
+
+static_assert(!stdr::input_range<test_non_const_range<input_iterator> const>);
+static_assert(!stdr::input_range<test_non_const_range<cxx20_input_iterator> const>);
+
+static_assert(stdr::input_range<test_common_range<input_iterator> >);
+static_assert(!stdr::input_range<test_common_range<cxx20_input_iterator> >);
+
+static_assert(stdr::input_range<test_common_range<input_iterator> const>);
+static_assert(!stdr::input_range<test_common_range<cxx20_input_iterator> const>);
+
+static_assert(stdr::input_range<test_non_const_common_range<input_iterator> >);
+static_assert(!stdr::input_range<test_non_const_common_range<cxx20_input_iterator> >);
+
+static_assert(!stdr::input_range<test_non_const_common_range<input_iterator> const>);
+static_assert(!stdr::input_range<test_non_const_common_range<cxx20_input_iterator> const>);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/ranges/range.refinements/subsumption.compile.pass.cpp
copy from libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp
copy to libcxx/test/std/ranges/range.refinements/subsumption.compile.pass.cpp
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/ranges/range.refinements/subsumption.compile.pass.cpp
@@ -11,17 +11,30 @@
 // UNSUPPORTED: gcc-10
 // XFAIL: msvc && clang
 
-// reverse_iterator
+// template<class T>
+// concept input_iterator;
+
+#include <ranges>
 
 #include <iterator>
 
-using iterator = std::reverse_iterator<int*>;
+struct range {
+  int* begin();
+  int* end();
+};
+
+// clang-format off
+template<std::ranges::range R>
+requires std::input_iterator<std::ranges::iterator_t<R> >
+[[nodiscard]] constexpr bool check_input_range_subsumption() {
+  return false;
+}
 
-static_assert(std::indirectly_readable<iterator>);
-static_assert(std::indirectly_writable<iterator, int>);
-static_assert(std::incrementable<iterator>);
-static_assert(std::input_or_output_iterator<iterator>);
-static_assert(std::sentinel_for<iterator, iterator>);
+template<std::ranges::input_range>
+requires true
+[[nodiscard]] constexpr bool check_input_range_subsumption() {
+  return true;
+}
+// clang-format on
 
-using other_iterator = std::reverse_iterator<float*>;
-static_assert(std::sentinel_for<iterator, other_iterator>);
+static_assert(check_input_range_subsumption<range>());
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
--- 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
@@ -22,3 +22,4 @@
 static_assert(std::incrementable<std::cregex_iterator>);
 static_assert(std::input_or_output_iterator<std::cregex_iterator>);
 static_assert(std::sentinel_for<std::cregex_iterator, std::cregex_iterator>);
+static_assert(std::input_iterator<std::cregex_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
--- 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
@@ -22,3 +22,4 @@
 static_assert(std::incrementable<std::cregex_token_iterator>);
 static_assert(std::input_or_output_iterator<std::cregex_token_iterator>);
 static_assert(std::sentinel_for<std::cregex_token_iterator, std::cregex_token_iterator>);
+static_assert(std::input_iterator<std::cregex_token_iterator>);
diff --git a/libcxx/test/std/re/re.results/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/re/re.results/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/re/re.results/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/re/re.results/range_concept_conformance.compile.pass.cpp
@@ -22,6 +22,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<std::cmatch>, std::cmatch::iterator>);
 static_assert(stdr::common_range<std::cmatch>);
+static_assert(stdr::input_range<std::cmatch>);
 
 static_assert(std::same_as<stdr::iterator_t<std::cmatch const>, std::cmatch::const_iterator>);
 static_assert(stdr::common_range<std::cmatch const>);
+static_assert(stdr::input_range<std::cmatch const>);
diff --git a/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp
@@ -22,6 +22,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<std::string>, std::string::iterator>);
 static_assert(stdr::common_range<std::string>);
+static_assert(stdr::input_range<std::string>);
 
 static_assert(std::same_as<stdr::iterator_t<std::string const>, std::string::const_iterator>);
 static_assert(stdr::common_range<std::string const>);
+static_assert(stdr::input_range<std::string const>);
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
--- 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
@@ -31,6 +31,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
@@ -39,3 +40,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/std/strings/string.view/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/strings/string.view/range_concept_conformance.compile.pass.cpp
--- a/libcxx/test/std/strings/string.view/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/strings/string.view/range_concept_conformance.compile.pass.cpp
@@ -22,6 +22,8 @@
 
 static_assert(std::same_as<stdr::iterator_t<std::string_view>, std::string_view::iterator>);
 static_assert(stdr::common_range<std::string_view>);
+static_assert(stdr::input_range<std::string_view>);
 
 static_assert(std::same_as<stdr::iterator_t<std::string_view const>, std::string_view::const_iterator>);
 static_assert(stdr::common_range<std::string_view const>);
+static_assert(stdr::input_range<std::string_view const>);
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
--- 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
@@ -30,6 +30,7 @@
 static_assert(std::sentinel_for<iterator, const_iterator>);
 static_assert(!std::sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<iterator>);
 
 static_assert(std::indirectly_readable<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, char>);
@@ -39,3 +40,4 @@
 static_assert(std::sentinel_for<const_iterator, const_iterator>);
 static_assert(!std::sentinel_for<const_iterator, reverse_iterator>);
 static_assert(!std::sentinel_for<const_iterator, const_reverse_iterator>);
+static_assert(std::input_iterator<const_iterator>);
diff --git a/libcxx/test/support/test_iterators.h b/libcxx/test/support/test_iterators.h
--- a/libcxx/test/support/test_iterators.h
+++ b/libcxx/test/support/test_iterators.h
@@ -632,6 +632,43 @@
 bool operator!= (const NonThrowingIterator<T>& a, const NonThrowingIterator<T>& b) TEST_NOEXCEPT
 {   return !a.operator==(b); }
 
+#if TEST_STD_VER > 17 && defined(__cpp_lib_concepts)
+
+template <class I>
+struct cxx20_input_iterator {
+  using value_type = std::iter_value_t<I>;
+  using difference_type = std::iter_difference_t<I>;
+  using iterator_concept = std::input_iterator_tag;
+
+  cxx20_input_iterator() = default;
+
+  cxx20_input_iterator(cxx20_input_iterator&&) = default;
+  cxx20_input_iterator& operator=(cxx20_input_iterator&&) = default;
+
+  cxx20_input_iterator(cxx20_input_iterator const&) = delete;
+  cxx20_input_iterator& operator=(cxx20_input_iterator const&) = delete;
+
+  explicit constexpr cxx20_input_iterator(I base) : base_(std::move(base)) {}
+
+  constexpr decltype(auto) operator*() const { return *base_; }
+
+  cxx20_input_iterator& operator++() {
+    ++base_;
+    return *this;
+  }
+
+  void operator++(int) { ++base_; }
+
+  [[nodiscard]] I const& base() const& { return base_; }
+
+  [[nodiscard]] I base() && { return std::move(base_); }
+
+private:
+  I base_ = I();
+};
+
+#endif // TEST_STD_VER > 17 && defined(__cpp_lib_concepts)
+
 #undef DELETE_FUNCTION
 
 #endif // ITERATORS_H
diff --git a/libcxx/test/support/test_range.h b/libcxx/test/support/test_range.h
--- a/libcxx/test/support/test_range.h
+++ b/libcxx/test/support/test_range.h
@@ -18,7 +18,7 @@
 #endif
 
 struct sentinel {
-  bool operator==(std::input_or_output_iterator auto) const;
+  bool operator==(std::input_or_output_iterator auto const&) const;
 };
 
 // clang-format off