diff --git a/libcxx/docs/Status/RangesAlgorithms.csv b/libcxx/docs/Status/RangesAlgorithms.csv
--- a/libcxx/docs/Status/RangesAlgorithms.csv
+++ b/libcxx/docs/Status/RangesAlgorithms.csv
@@ -21,8 +21,8 @@
 Search,min_element,Nikolas Klauser,n/a,✅
 Search,max_element,Not assigned,n/a,Not started
 Search,minmax_element,Not assigned,n/a,Not started
-Search,count,Not assigned,n/a,Not started
-Search,count_if,Not assigned,n/a,Not started
+Search,count,Nikolas Klauser, `D121523 <https://llvm.org/D121523>`_,✅
+Search,count_if,Nikolas Klauser, `D121523 <https://llvm.org/D121523>`_,✅
 Search,search,Not assigned,n/a,Not started
 Search,search_n,Not assigned,n/a,Not started
 Search,find_end,Not assigned,n/a,Not started
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -66,6 +66,8 @@
   __algorithm/pop_heap.h
   __algorithm/prev_permutation.h
   __algorithm/push_heap.h
+  __algorithm/ranges_count.h
+  __algorithm/ranges_count_if.h
   __algorithm/ranges_find.h
   __algorithm/ranges_find_if.h
   __algorithm/ranges_find_if_not.h
diff --git a/libcxx/include/__algorithm/ranges_count.h b/libcxx/include/__algorithm/ranges_count.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__algorithm/ranges_count.h
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___ALGORITHM_RANGES_COUNT_H
+#define _LIBCPP___ALGORITHM_RANGES_COUNT_H
+
+#include <__algorithm/ranges_count_if.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/incrementable_traits.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+namespace __count {
+struct __fn {
+  template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, class _Proj = identity>
+    requires indirect_binary_predicate<ranges::equal_to, projected<_Ip, _Proj>, const _Tp*>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  iter_difference_t<_Ip> operator()(_Ip __first, _Sp __last, const _Tp& __value, _Proj __proj = {}) const {
+    auto __pred = [&](const auto& __e) { return __e == __value; };
+    return ranges::__count_if_impl(std::move(__first), std::move(__last), __pred, __proj);
+  }
+
+  template <input_range _Rp, class _Tp, class _Proj = identity>
+    requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<_Rp>, _Proj>, const _Tp*>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  range_difference_t<_Rp> operator()(_Rp&& __r, const _Tp& __value, _Proj __proj = {}) const {
+    auto __pred = [&](const auto& __e) { return __e == __value; };
+    return ranges::__count_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
+  }
+};
+} // namespace __count
+
+inline namespace __cpo {
+  inline constexpr auto count = __count::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_COUNT_H
diff --git a/libcxx/include/__algorithm/ranges_count_if.h b/libcxx/include/__algorithm/ranges_count_if.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__algorithm/ranges_count_if.h
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___ALGORITHM_RANGES_COUNT_IF_H
+#define _LIBCPP___ALGORITHM_RANGES_COUNT_IF_H
+
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/incrementable_traits.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+template <class _Ip, class _Sp, class _Proj, class _Pred>
+_LIBCPP_HIDE_FROM_ABI constexpr
+auto __count_if_impl(_Ip __first, _Sp __last, _Pred& __pred, _Proj& __proj) {
+  iter_difference_t<_Ip> __counter(0);
+  for (; __first != __last; ++__first) {
+    if (std::invoke(__pred, std::invoke(__proj, *__first)))
+      ++__counter;
+  }
+  return __counter;
+}
+
+namespace __count_if {
+struct __fn {
+  template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Proj = identity,
+            indirect_unary_predicate<projected<_Ip, _Proj>> _Pred>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  iter_difference_t<_Ip> operator()(_Ip __first, _Sp __last, _Pred __pred, _Proj __proj = {}) const {
+    return ranges::__count_if_impl(std::move(__first), std::move(__last), __pred, __proj);
+  }
+
+  template <input_range _Rp, class _Proj = identity,
+            indirect_unary_predicate<projected<iterator_t<_Rp>, _Proj>> _Pred>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  range_difference_t<_Rp> operator()(_Rp&& __r, _Pred __pred, _Proj __proj = {}) const {
+    return ranges::__count_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
+  }
+};
+} // namespace __count_if
+
+inline namespace __cpo {
+  inline constexpr auto count_if = __count_if::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_COUNT_IF_H
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -83,6 +83,27 @@
            indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
     constexpr borrowed_iterator_t<R>
       find_if_not(R&& r, Pred pred, Proj proj = {});                                // since C++20
+
+
+  template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
+    requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
+    constexpr iter_difference_t<I>
+      ranges::count(I first, S last, const T& value, Proj proj = {});               // since C++20
+
+  template<input_range R, class T, class Proj = identity>
+    requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
+    constexpr range_difference_t<R>
+      ranges::count(R&& r, const T& value, Proj proj = {});                         // since C++20
+
+  template<input_iterator I, sentinel_for<I> S, class Proj = identity,
+           indirect_unary_predicate<projected<I, Proj>> Pred>
+    constexpr iter_difference_t<I>
+      ranges::count_if(I first, S last, Pred pred, Proj proj = {});                 // since C++20
+
+  template<input_range R, class Proj = identity,
+           indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
+    constexpr range_difference_t<R>
+      ranges::count_if(R&& r, Pred pred, Proj proj = {});                           // since C++20
 }
 
 template <class InputIterator, class Predicate>
@@ -802,6 +823,8 @@
 #include <__algorithm/pop_heap.h>
 #include <__algorithm/prev_permutation.h>
 #include <__algorithm/push_heap.h>
+#include <__algorithm/ranges_count.h>
+#include <__algorithm/ranges_count_if.h>
 #include <__algorithm/ranges_find.h>
 #include <__algorithm/ranges_find_if.h>
 #include <__algorithm/ranges_find_if_not.h>
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -294,6 +294,8 @@
       module pop_heap                 { private header "__algorithm/pop_heap.h" }
       module prev_permutation         { private header "__algorithm/prev_permutation.h" }
       module push_heap                { private header "__algorithm/push_heap.h" }
+      module ranges_count             { private header "__algorithm/ranges_count.h" }
+      module ranges_count_if          { private header "__algorithm/ranges_count_if.h" }
       module ranges_find              { private header "__algorithm/ranges_find.h" }
       module ranges_find_if           { private header "__algorithm/ranges_find_if.h" }
       module ranges_find_if_not       { private header "__algorithm/ranges_find_if_not.h" }
diff --git a/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_count.module.verify.cpp b/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_count.module.verify.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_count.module.verify.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-build
+
+// WARNING: This test was generated by 'generate_private_header_tests.py'
+// and should not be edited manually.
+
+// expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_count.h'}}
+#include <__algorithm/ranges_count.h>
diff --git a/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_count_if.module.verify.cpp b/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_count_if.module.verify.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_count_if.module.verify.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-build
+
+// WARNING: This test was generated by 'generate_private_header_tests.py'
+// and should not be edited manually.
+
+// expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_count_if.h'}}
+#include <__algorithm/ranges_count_if.h>
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/ranges.count.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/ranges.count.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/ranges.count.pass.cpp
@@ -0,0 +1,156 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-has-no-incomplete-ranges
+
+// template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
+//   requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
+//   constexpr iter_difference_t<I>
+//     ranges::count(I first, S last, const T& value, Proj proj = {});
+// template<input_range R, class T, class Proj = identity>
+//   requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
+//   constexpr range_difference_t<R>
+//     ranges::count(R&& r, const T& value, Proj proj = {});
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <ranges>
+
+#include "almost_satisfies_types.h"
+#include "test_iterators.h"
+
+struct NotEqualityComparable {};
+
+template <class It, class Sent = It>
+concept HasFindIt = requires(It it, Sent sent) { std::ranges::count(it, sent, *it); };
+static_assert(HasFindIt<int*>);
+static_assert(!HasFindIt<NotEqualityComparable*>);
+static_assert(!HasFindIt<InputIteratorNotDerivedFrom>);
+static_assert(!HasFindIt<InputIteratorNotIndirectlyReadable>);
+static_assert(!HasFindIt<InputIteratorNotInputOrOutputIterator>);
+static_assert(!HasFindIt<cpp20_input_iterator<int*>, SentinelForNotSemiregular>);
+static_assert(!HasFindIt<cpp20_input_iterator<int*>, InputRangeNotSentinelEqualityComparableWith>);
+
+static_assert(!HasFindIt<int*, int>);
+static_assert(!HasFindIt<int, int*>);
+
+template <class Range, class ValT>
+concept HasFindR = requires(Range r) { std::ranges::count(r, ValT{}); };
+static_assert(HasFindR<std::array<int, 1>, int>);
+static_assert(!HasFindR<int, int>);
+static_assert(!HasFindR<std::array<NotEqualityComparable, 1>, NotEqualityComparable>);
+static_assert(!HasFindR<InputRangeNotDerivedFrom, int>);
+static_assert(!HasFindR<InputRangeNotIndirectlyReadable, int>);
+static_assert(!HasFindR<InputRangeNotInputOrOutputIterator, int>);
+static_assert(!HasFindR<InputRangeNotSentinelSemiregular, int>);
+static_assert(!HasFindR<InputRangeNotSentinelEqualityComparableWith, int>);
+
+template <class It, class Sent = It>
+constexpr void test_iterators() {
+  {
+    int a[] = {1, 2, 3, 4};
+    std::same_as<std::ptrdiff_t> auto ret = std::ranges::count(It(a), Sent(It(a + 4)), 4);
+    assert(ret == 1);
+  }
+  {
+    int a[] = {1, 2, 3, 4};
+    auto range = std::ranges::subrange(It(a), Sent(It(a + 4)));
+    std::same_as<std::ptrdiff_t> auto ret = std::ranges::count(range, 4);
+    assert(ret == 1);
+  }
+}
+
+constexpr bool test() {
+  test_iterators<int*>();
+  test_iterators<const int*>();
+  test_iterators<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>();
+  test_iterators<bidirectional_iterator<int*>>();
+  test_iterators<forward_iterator<int*>>();
+  test_iterators<random_access_iterator<int*>>();
+  test_iterators<contiguous_iterator<int*>>();
+
+  {
+    // check that projections are used properly and that they are called with the iterator directly
+    {
+      int a[] = {1, 2, 3, 4};
+      auto ret = std::ranges::count(a, a + 4, a + 3, [](int& i) { return &i; });
+      assert(ret == 1);
+    }
+    {
+      int a[] = {1, 2, 3, 4};
+      auto ret = std::ranges::count(a, a + 3, [](int& i) { return &i; });
+      assert(ret == 1);
+    }
+  }
+
+  { // check that 0 is returned with no match
+    {
+      int a[] = {1, 1, 1};
+      auto ret = std::ranges::count(a, a + 3, 0);
+      assert(ret == 0);
+    }
+    {
+      int a[] = {1, 1, 1};
+      auto ret = std::ranges::count(a, 0);
+      assert(ret == 0);
+    }
+  }
+
+  {
+    // check that std::invoke is used
+    struct S { int i; };
+    S a[] = { S{1}, S{3}, S{2} };
+    std::same_as<std::ptrdiff_t> auto ret = std::ranges::count(a, 4, &S::i);
+    assert(ret == 0);
+  }
+
+  {
+    // count invocations of the projection
+    {
+      int a[] = {1, 2, 3, 4};
+      int projection_count = 0;
+      auto ret = std::ranges::count(a, a + 4, 2, [&](int i) { ++projection_count; return i; });
+      assert(ret == 1);
+      assert(projection_count == 4);
+    }
+    {
+      int a[] = {1, 2, 3, 4};
+      int projection_count = 0;
+      auto ret = std::ranges::count(a, 2, [&](int i) { ++projection_count; return i; });
+      assert(ret == 1);
+      assert(projection_count == 4);
+    }
+  }
+
+  {
+    // check that an empty range works
+    {
+      std::array<int ,0> a = {};
+      auto ret = std::ranges::count(a.begin(), a.end(), 1);
+      assert(ret == 0);
+    }
+    {
+      std::array<int, 0> a = {};
+      auto ret = std::ranges::count(a, 1);
+      assert(ret == 0);
+    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/ranges.count_if.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/ranges.count_if.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/ranges.count_if.pass.cpp
@@ -0,0 +1,187 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-has-no-incomplete-ranges
+
+// template<input_iterator I, sentinel_for<I> S, class Proj = identity,
+//          indirect_unary_predicate<projected<I, Proj>> Pred>
+//   constexpr iter_difference_t<I>
+//     ranges::count_if(I first, S last, Pred pred, Proj proj = {});
+// template<input_range R, class Proj = identity,
+//          indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
+//   constexpr range_difference_t<R>
+//     ranges::count_if(R&& r, Pred pred, Proj proj = {});
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <ranges>
+
+#include "almost_satisfies_types.h"
+#include "test_iterators.h"
+
+struct Predicate {
+  bool operator()(int);
+};
+
+template <class It, class Sent = It>
+concept HasCountIfIt = requires(It it, Sent sent) { std::ranges::count_if(it, sent, Predicate{}); };
+static_assert(HasCountIfIt<int*>);
+static_assert(!HasCountIfIt<InputIteratorNotDerivedFrom>);
+static_assert(!HasCountIfIt<InputIteratorNotIndirectlyReadable>);
+static_assert(!HasCountIfIt<InputIteratorNotInputOrOutputIterator>);
+static_assert(!HasCountIfIt<cpp20_input_iterator<int*>, SentinelForNotSemiregular>);
+static_assert(!HasCountIfIt<cpp20_input_iterator<int*>, InputRangeNotSentinelEqualityComparableWith>);
+
+static_assert(!HasCountIfIt<int*, int>);
+static_assert(!HasCountIfIt<int, int*>);
+
+template <class Pred>
+concept HasFindIfPred = requires(int* it, Pred pred) {std::ranges::count_if(it, it, pred); };
+
+static_assert(!HasFindIfPred<IndirectUnaryPredicateNotCopyConstructible>);
+static_assert(!HasFindIfPred<IndirectUnaryPredicateNotPredicate>);
+
+template <class R>
+concept HasCountIfR = requires(R r) { std::ranges::count_if(r, Predicate{}); };
+static_assert(HasCountIfR<std::array<int, 0>>);
+static_assert(!HasCountIfR<int>);
+static_assert(!HasCountIfR<InputRangeNotDerivedFrom>);
+static_assert(!HasCountIfR<InputRangeNotIndirectlyReadable>);
+static_assert(!HasCountIfR<InputRangeNotInputOrOutputIterator>);
+static_assert(!HasCountIfR<InputRangeNotSentinelSemiregular>);
+static_assert(!HasCountIfR<InputRangeNotSentinelEqualityComparableWith>);
+
+template <class It, class Sent = It>
+constexpr void test_iterators() {
+  {
+    int a[] = {1, 2, 3, 4};
+    std::same_as<std::ptrdiff_t> auto ret =
+      std::ranges::count_if(It(a), Sent(It(a + 4)), [](int x) mutable { return x == 4; });
+    assert(ret == 1);
+  }
+  {
+    int a[] = {1, 2, 3, 4};
+    auto range = std::ranges::subrange(It(a), Sent(It(a + 4)));
+    std::same_as<std::ptrdiff_t> auto ret =
+      std::ranges::count_if(range, [](int x) mutable { return x == 4; });
+    assert(ret == 1);
+  }
+}
+
+constexpr bool test() {
+  test_iterators<int*>();
+  test_iterators<const int*>();
+  test_iterators<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>();
+  test_iterators<bidirectional_iterator<int*>>();
+  test_iterators<forward_iterator<int*>>();
+  test_iterators<random_access_iterator<int*>>();
+  test_iterators<contiguous_iterator<int*>>();
+
+  {
+    // check that projections are used properly and that they are called with the iterator directly
+    {
+      int a[] = {1, 2, 3, 4};
+      auto ret = std::ranges::count_if(a, a + 4, [&](int* i) { return i == a + 3; }, [](int& i) { return &i; });
+      assert(ret == 1);
+    }
+    {
+      int a[] = {1, 2, 3, 4};
+      auto ret = std::ranges::count_if(a, [&](int* i) { return i == a + 3; }, [](int& i) { return &i; });
+      assert(ret == 1);
+    }
+  }
+
+  {
+    // check that std::invoke is used
+    {
+      struct S {
+        int comp;
+        int other;
+      };
+      S a[] = { {0, 0}, {0, 2}, {0, 1} };
+      auto ret = std::ranges::count_if(a, [](int i){ return i == 0; }, &S::comp);
+      assert(ret == 3);
+    }
+    {
+      struct S {
+        int comp;
+        int other;
+      };
+      S a[] = { {0, 0}, {0, 2}, {0, 1} };
+      auto ret = std::ranges::count_if(a, a + 3, [](int i) { return i == 0; }, &S::comp);
+      assert(ret == 3);
+    }
+  }
+
+  {
+    // check that 0 is returned with no match
+    {
+      int a[] = {1, 1, 1};
+      auto ret = std::ranges::count_if(a, a + 3, [](int) { return false; });
+      assert(ret == 0);
+    }
+    {
+      int a[] = {1, 1, 1};
+      auto ret = std::ranges::count_if(a, [](int){ return false; });
+      assert(ret == 0);
+    }
+  }
+
+  {
+    // count projection and predicate invocation count
+    {
+      int a[] = {1, 2, 3, 4};
+      int predicate_count = 0;
+      int projection_count = 0;
+      auto ret = std::ranges::count_if(a, a + 4,
+                                       [&](int i) { ++predicate_count; return i == 2; },
+                                       [&](int i) { ++projection_count; return i; });
+      assert(ret == 1);
+      assert(predicate_count == 4);
+      assert(projection_count == 4);
+    }
+    {
+      int a[] = {1, 2, 3, 4};
+      int predicate_count = 0;
+      int projection_count = 0;
+      auto ret = std::ranges::count_if(a,
+                                       [&](int i) { ++predicate_count; return i == 2; },
+                                       [&](int i) { ++projection_count; return i; });
+      assert(ret == 1);
+      assert(predicate_count == 4);
+      assert(projection_count == 4);
+    }
+  }
+
+  {
+    // check that an empty range works
+    {
+      std::array<int ,0> a = {};
+      auto ret = std::ranges::count_if(a.begin(), a.end(), [](int) { return true; });
+      assert(ret == 0);
+    }
+    {
+      std::array<int, 0> a = {};
+      auto ret = std::ranges::count_if(a, [](int) { return true; });
+      assert(ret == 0);
+    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
--- a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
+++ b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
@@ -70,8 +70,8 @@
 //static_assert(test(std::ranges::copy_backward, a, a));
 //static_assert(test(std::ranges::copy_if, a, a, odd));
 //static_assert(test(std::ranges::copy_n, a, 10, a));
-//static_assert(test(std::ranges::count, a, 42));
-//static_assert(test(std::ranges::count_if, a, odd));
+static_assert(test(std::ranges::count, a, 42));
+static_assert(test(std::ranges::count_if, a, odd));
 //static_assert(test(std::ranges::ends_with, a, a));
 //static_assert(test(std::ranges::equal, a, a));
 //static_assert(test(std::ranges::equal_range, a, 42));