diff --git a/libcxx/include/__compare/strong_order.h b/libcxx/include/__compare/strong_order.h
--- a/libcxx/include/__compare/strong_order.h
+++ b/libcxx/include/__compare/strong_order.h
@@ -86,11 +86,11 @@
                 bool __u_is_nan = _VSTD::isnan(__u);
                 bool __t_is_negative = _VSTD::signbit(__t);
                 bool __u_is_negative = _VSTD::signbit(__u);
-                using _IntType = std::conditional_t<
-                    sizeof(__t) == sizeof(int32_t), int32_t, std::conditional_t<
+                using _IntType = conditional_t<
+                    sizeof(__t) == sizeof(int32_t), int32_t, conditional_t<
                     sizeof(__t) == sizeof(int64_t), int64_t, void>
                 >;
-                if constexpr (std::is_same_v<_IntType, void>) {
+                if constexpr (is_same_v<_IntType, void>) {
                     static_assert(sizeof(_Dp) == 0, "std::strong_order is unimplemented for this floating-point type");
                 } else if (__t_is_nan && __u_is_nan) {
                     // Order by sign bit, then by "payload bits" (we'll just use bit_cast).
diff --git a/libcxx/include/__compare/weak_order.h b/libcxx/include/__compare/weak_order.h
--- a/libcxx/include/__compare/weak_order.h
+++ b/libcxx/include/__compare/weak_order.h
@@ -42,13 +42,13 @@
         _LIBCPP_HIDE_FROM_ABI static constexpr weak_ordering
         __go(_Tp&& __t, _Up&& __u, __priority_tag<2>) noexcept
         {
-            std::partial_ordering __po = (__t <=> __u);
-            if (__po == std::partial_ordering::less) {
-                return std::weak_ordering::less;
-            } else if (__po == std::partial_ordering::equivalent) {
-                return std::weak_ordering::equivalent;
-            } else if (__po == std::partial_ordering::greater) {
-                return std::weak_ordering::greater;
+            partial_ordering __po = (__t <=> __u);
+            if (__po == partial_ordering::less) {
+                return weak_ordering::less;
+            } else if (__po == partial_ordering::equivalent) {
+                return weak_ordering::equivalent;
+            } else if (__po == partial_ordering::greater) {
+                return weak_ordering::greater;
             } else {
                 // Otherwise, at least one of them is a NaN.
                 bool __t_is_nan = _VSTD::isnan(__t);
diff --git a/libcxx/include/__ranges/counted.h b/libcxx/include/__ranges/counted.h
--- a/libcxx/include/__ranges/counted.h
+++ b/libcxx/include/__ranges/counted.h
@@ -9,6 +9,7 @@
 #ifndef _LIBCPP___RANGES_COUNTED_H
 #define _LIBCPP___RANGES_COUNTED_H
 
+#include <__concepts/convertible_to.h>
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/counted_iterator.h>
@@ -16,10 +17,7 @@
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/iterator_traits.h>
 #include <__memory/pointer_traits.h>
-#include <__ranges/concepts.h>
 #include <__ranges/subrange.h>
-#include <__utility/decay_copy.h>
-#include <__utility/declval.h>
 #include <__utility/forward.h>
 #include <__utility/move.h>
 #include <span>
@@ -36,50 +34,44 @@
 namespace ranges::views {
 
 namespace __counted {
+
   template<class _From, class _To>
   concept __explicitly_convertible = requires {
     _To(_From{});
   };
 
   struct __fn {
-    template<class _Iter, class _Diff>
-      requires contiguous_iterator<decay_t<_Iter>> &&
-               __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
+    template<contiguous_iterator _It>
     _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Iter&& __it, _Diff __c) const
-      noexcept(noexcept(
-        span(_VSTD::to_address(__it), static_cast<iter_difference_t<_Iter>>(__c))
-      ))
-    {
-      return span(_VSTD::to_address(__it), static_cast<iter_difference_t<_Iter>>(__c));
-    }
-
-    template<class _Iter, class _Diff>
-      requires random_access_iterator<decay_t<_Iter>> &&
-               __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(span(_VSTD::to_address(__it), static_cast<size_t>(__count))))
+      // Deliberately omit return-type SFINAE, because to_address is not SFINAE-friendly
+      { return          span(_VSTD::to_address(__it), static_cast<size_t>(__count)); }
+
+    template<random_access_iterator _It>
     _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Iter&& __it, _Diff __c) const
-      noexcept(
-        noexcept(__it + static_cast<iter_difference_t<_Iter>>(__c)) &&
-        noexcept(ranges::subrange(_VSTD::forward<_Iter>(__it), _VSTD::__decay_copy(__it)))
-      )
-    {
-      auto __last = __it + static_cast<iter_difference_t<_Iter>>(__c);
-      return ranges::subrange(_VSTD::forward<_Iter>(__it), _VSTD::move(__last));
-    }
-
-    template<class _Iter, class _Diff>
-      requires __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(subrange(__it, __it + __count)))
+      -> decltype(      subrange(__it, __it + __count))
+      { return          subrange(__it, __it + __count); }
+
+    template<class _It>
     _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Iter&& __it, _Diff __c) const
-      noexcept(noexcept(
-        ranges::subrange(counted_iterator(_VSTD::forward<_Iter>(__it), __c), default_sentinel)
-      ))
-    {
-      return ranges::subrange(counted_iterator(_VSTD::forward<_Iter>(__it), __c), default_sentinel);
-    }
+    static constexpr auto __go(_It&& __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(subrange(counted_iterator(_VSTD::forward<_It>(__it), __count), default_sentinel)))
+      -> decltype(      subrange(counted_iterator(_VSTD::forward<_It>(__it), __count), default_sentinel))
+      { return          subrange(counted_iterator(_VSTD::forward<_It>(__it), __count), default_sentinel); }
+
+    template<class _It, convertible_to<iter_difference_t<_It>> _Diff>
+      requires input_or_output_iterator<decay_t<_It>>
+    [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
+    constexpr auto operator()(_It&& __it, _Diff&& __count) const
+      noexcept(noexcept(__go(_VSTD::forward<_It>(__it), _VSTD::forward<_Diff>(__count))))
+      -> decltype(      __go(_VSTD::forward<_It>(__it), _VSTD::forward<_Diff>(__count)))
+      { return          __go(_VSTD::forward<_It>(__it), _VSTD::forward<_Diff>(__count)); }
   };
-}
+
+} // namespace __counted
 
 inline namespace __cpo {
   inline constexpr auto counted = __counted::__fn{};
diff --git a/libcxx/include/__ranges/subrange.h b/libcxx/include/__ranges/subrange.h
--- a/libcxx/include/__ranges/subrange.h
+++ b/libcxx/include/__ranges/subrange.h
@@ -91,14 +91,14 @@
     _LIBCPP_HIDE_FROM_ABI
     constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent)
       requires _MustProvideSizeAtConstruction
-      : __begin_(_VSTD::move(__iter)), __end_(std::move(__sent))
+      : __begin_(_VSTD::move(__iter)), __end_(_VSTD::move(__sent))
     { }
 
     _LIBCPP_HIDE_FROM_ABI
     constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent,
                        make_unsigned_t<iter_difference_t<_Iter>> __n)
       requires (_Kind == subrange_kind::sized)
-      : __begin_(_VSTD::move(__iter)), __end_(std::move(__sent)), __size_(__n)
+      : __begin_(_VSTD::move(__iter)), __end_(_VSTD::move(__sent)), __size_(__n)
     {
       if constexpr (sized_sentinel_for<_Sent, _Iter>)
         _LIBCPP_ASSERT((__end_ - __begin_) == static_cast<iter_difference_t<_Iter>>(__n),
diff --git a/libcxx/test/std/ranges/range.adaptors/range.counted/counted.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.counted/counted.pass.cpp
--- a/libcxx/test/std/ranges/range.adaptors/range.counted/counted.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.counted/counted.pass.cpp
@@ -20,183 +20,205 @@
 #include "test_macros.h"
 #include "test_iterators.h"
 
-struct Unrelated {};
-
-struct ConvertibleToSize {
-  constexpr operator std::ptrdiff_t() const { return 8; }
+struct Convertible {
+  operator int() const;
 };
 
-struct ImplicitlyConvertible {
-    operator short();
-    explicit operator std::ptrdiff_t() = delete;
+struct OnlyExplicitlyConvertible {
+  explicit operator int() const;
 };
 
-template<class Iter, class T>
-concept CountedInvocable = requires(Iter& i, T t) { std::views::counted(i, t); };
+template<class... Ts>
+concept CountedInvocable = requires (Ts&&... ts) {
+  std::views::counted(std::forward<Ts>(ts)...);
+};
 
 constexpr bool test() {
   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
 
   {
-    static_assert( CountedInvocable<contiguous_iterator<int*>, ConvertibleToSize>);
-    static_assert(!CountedInvocable<contiguous_iterator<int*>, ImplicitlyConvertible>);
-    static_assert(!CountedInvocable<contiguous_iterator<int*>, Unrelated>);
+    static_assert(std::addressof(std::views::counted) == std::addressof(std::ranges::views::counted));
+
+    auto copy = std::views::counted;
+    static_assert(std::semiregular<decltype(copy)>);
+
+    static_assert( CountedInvocable<int*, size_t>);
+    static_assert( CountedInvocable<int*, Convertible>);
+    static_assert(!CountedInvocable<int*, OnlyExplicitlyConvertible>);
+    static_assert(!CountedInvocable<int*, int*>);
+    static_assert(!CountedInvocable<int*>);
+    static_assert(!CountedInvocable<size_t>);
+    static_assert(!CountedInvocable<>);
+  }
+
+  {
+    auto c1 = std::views::counted(buffer, 3);
+    auto c2 = std::views::counted(std::as_const(buffer), 3);
+
+    ASSERT_SAME_TYPE(decltype(c1), std::span<int>);
+    ASSERT_SAME_TYPE(decltype(c2), std::span<const int>);
+
+    assert(c1.data() == buffer && c1.size() == 3);
+    assert(c2.data() == buffer && c2.size() == 3);
+  }
+
+  {
+    auto it = contiguous_iterator<int*>(buffer);
+    auto cit = contiguous_iterator<const int*>(buffer);
+
+    auto c1 = std::views::counted(it, 3);
+    auto c2 = std::views::counted(std::as_const(it), 3);
+    auto c3 = std::views::counted(std::move(it), 3);
+    auto c4 = std::views::counted(contiguous_iterator<int*>(buffer), 3);
+    auto c5 = std::views::counted(cit, 3);
+    auto c6 = std::views::counted(std::as_const(cit), 3);
+    auto c7 = std::views::counted(std::move(cit), 3);
+    auto c8 = std::views::counted(contiguous_iterator<const int*>(buffer), 3);
+
+    ASSERT_SAME_TYPE(decltype(c1), std::span<int>);
+    ASSERT_SAME_TYPE(decltype(c2), std::span<int>);
+    ASSERT_SAME_TYPE(decltype(c3), std::span<int>);
+    ASSERT_SAME_TYPE(decltype(c4), std::span<int>);
+    ASSERT_SAME_TYPE(decltype(c5), std::span<const int>);
+    ASSERT_SAME_TYPE(decltype(c6), std::span<const int>);
+    ASSERT_SAME_TYPE(decltype(c7), std::span<const int>);
+    ASSERT_SAME_TYPE(decltype(c8), std::span<const int>);
+
+    assert(c1.data() == buffer && c1.size() == 3);
+    assert(c2.data() == buffer && c2.size() == 3);
+    assert(c3.data() == buffer && c3.size() == 3);
+    assert(c4.data() == buffer && c4.size() == 3);
+    assert(c5.data() == buffer && c5.size() == 3);
+    assert(c6.data() == buffer && c6.size() == 3);
+    assert(c7.data() == buffer && c7.size() == 3);
+    assert(c8.data() == buffer && c8.size() == 3);
+  }
 
-    static_assert(std::semiregular<std::remove_const_t<decltype(std::views::counted)>>);
+  {
+    auto it = random_access_iterator<int*>(buffer);
+    auto cit = random_access_iterator<const int*>(buffer);
+
+    auto c1 = std::views::counted(it, 3);
+    auto c2 = std::views::counted(std::as_const(it), 3);
+    auto c3 = std::views::counted(std::move(it), 3);
+    auto c4 = std::views::counted(random_access_iterator<int*>(buffer), 3);
+    auto c5 = std::views::counted(cit, 3);
+    auto c6 = std::views::counted(std::as_const(cit), 3);
+    auto c7 = std::views::counted(std::move(cit), 3);
+    auto c8 = std::views::counted(random_access_iterator<const int*>(buffer), 3);
+
+    ASSERT_SAME_TYPE(decltype(c1), std::ranges::subrange<random_access_iterator<int*>>);
+    ASSERT_SAME_TYPE(decltype(c2), std::ranges::subrange<random_access_iterator<int*>>);
+    ASSERT_SAME_TYPE(decltype(c3), std::ranges::subrange<random_access_iterator<int*>>);
+    ASSERT_SAME_TYPE(decltype(c4), std::ranges::subrange<random_access_iterator<int*>>);
+    ASSERT_SAME_TYPE(decltype(c5), std::ranges::subrange<random_access_iterator<const int*>>);
+    ASSERT_SAME_TYPE(decltype(c6), std::ranges::subrange<random_access_iterator<const int*>>);
+    ASSERT_SAME_TYPE(decltype(c7), std::ranges::subrange<random_access_iterator<const int*>>);
+    ASSERT_SAME_TYPE(decltype(c8), std::ranges::subrange<random_access_iterator<const int*>>);
+
+    assert(c1.begin() == it && c1.end() == it + 3);
+    assert(c2.begin() == it && c2.end() == it + 3);
+    assert(c3.begin() == it && c3.end() == it + 3);
+    assert(c4.begin() == it && c4.end() == it + 3);
+    assert(c5.begin() == cit && c5.end() == cit + 3);
+    assert(c6.begin() == cit && c6.end() == cit + 3);
+    assert(c7.begin() == cit && c7.end() == cit + 3);
+    assert(c8.begin() == cit && c8.end() == cit + 3);
   }
 
   {
-    {
-      contiguous_iterator<int*> iter(buffer);
-      std::span<int> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.data() == buffer);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::span<int>);
-    }
-    {
-      const contiguous_iterator<int*> iter(buffer);
-      std::span<int> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.data() == buffer);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::span<int>);
-    }
-    {
-      contiguous_iterator<const int*> iter(buffer);
-      std::span<const int> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.data() == buffer);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::span<const int>);
-    }
-    {
-      const contiguous_iterator<const int*> iter(buffer);
-      std::span<const int> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.data() == buffer);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::span<const int>);
-    }
+    auto it = bidirectional_iterator<int*>(buffer);
+    auto cit = bidirectional_iterator<const int*>(buffer);
+
+    auto c1 = std::views::counted(it, 3);
+    auto c2 = std::views::counted(std::as_const(it), 3);
+    auto c3 = std::views::counted(std::move(it), 3);
+    auto c4 = std::views::counted(bidirectional_iterator<int*>(buffer), 3);
+    auto c5 = std::views::counted(cit, 3);
+    auto c6 = std::views::counted(std::as_const(cit), 3);
+    auto c7 = std::views::counted(std::move(cit), 3);
+    auto c8 = std::views::counted(bidirectional_iterator<const int*>(buffer), 3);
+
+    using Expected = std::ranges::subrange<std::counted_iterator<decltype(it)>, std::default_sentinel_t>;
+    using ConstExpected = std::ranges::subrange<std::counted_iterator<decltype(cit)>, std::default_sentinel_t>;
+
+    ASSERT_SAME_TYPE(decltype(c1), Expected);
+    ASSERT_SAME_TYPE(decltype(c2), Expected);
+    ASSERT_SAME_TYPE(decltype(c3), Expected);
+    ASSERT_SAME_TYPE(decltype(c4), Expected);
+    ASSERT_SAME_TYPE(decltype(c5), ConstExpected);
+    ASSERT_SAME_TYPE(decltype(c6), ConstExpected);
+    ASSERT_SAME_TYPE(decltype(c7), ConstExpected);
+    ASSERT_SAME_TYPE(decltype(c8), ConstExpected);
+
+    assert(c1.begin().base() == it && c1.size() == 3);
+    assert(c2.begin().base() == it && c2.size() == 3);
+    assert(c3.begin().base() == it && c3.size() == 3);
+    assert(c4.begin().base() == it && c4.size() == 3);
+    assert(c5.begin().base() == cit && c5.size() == 3);
+    assert(c6.begin().base() == cit && c6.size() == 3);
+    assert(c7.begin().base() == cit && c7.size() == 3);
+    assert(c8.begin().base() == cit && c8.size() == 3);
   }
 
   {
-    {
-      random_access_iterator<int*> iter(buffer);
-      std::ranges::subrange<random_access_iterator<int*>> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == iter);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::ranges::subrange<random_access_iterator<int*>>);
-    }
-    {
-      const random_access_iterator<int*> iter(buffer);
-      std::ranges::subrange<random_access_iterator<int*>> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == iter);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::ranges::subrange<random_access_iterator<int*>>);
-    }
-    {
-      random_access_iterator<const int*> iter(buffer);
-      std::ranges::subrange<random_access_iterator<const int*>> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == iter);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::ranges::subrange<random_access_iterator<const int*>>);
-    }
-    {
-      const random_access_iterator<const int*> iter(buffer);
-      std::ranges::subrange<random_access_iterator<const int*>> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == iter);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)), std::ranges::subrange<random_access_iterator<const int*>>);
-    }
+    auto it = output_iterator<int*>(buffer);
+
+    auto c1 = std::views::counted(it, 3);
+    auto c2 = std::views::counted(std::as_const(it), 3);
+    auto c3 = std::views::counted(std::move(it), 3);
+    auto c4 = std::views::counted(output_iterator<int*>(buffer), 3);
+
+    using Expected = std::ranges::subrange<std::counted_iterator<decltype(it)>, std::default_sentinel_t>;
+
+    ASSERT_SAME_TYPE(decltype(c1), Expected);
+    ASSERT_SAME_TYPE(decltype(c2), Expected);
+    ASSERT_SAME_TYPE(decltype(c3), Expected);
+    ASSERT_SAME_TYPE(decltype(c4), Expected);
+
+    assert(base(c1.begin().base()) == buffer && c1.size() == 3);
+    assert(base(c2.begin().base()) == buffer && c2.size() == 3);
+    assert(base(c3.begin().base()) == buffer && c3.size() == 3);
+    assert(base(c4.begin().base()) == buffer && c4.size() == 3);
   }
 
   {
-    {
-      bidirectional_iterator<int*> iter(buffer);
-      std::ranges::subrange<
-        std::counted_iterator<bidirectional_iterator<int*>>,
-        std::default_sentinel_t> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == std::counted_iterator(iter, 8));
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)),
-                       std::ranges::subrange<
-                         std::counted_iterator<bidirectional_iterator<int*>>,
-                         std::default_sentinel_t>);
-    }
-    {
-      const bidirectional_iterator<int*> iter(buffer);
-      std::ranges::subrange<
-        std::counted_iterator<bidirectional_iterator<int*>>,
-        std::default_sentinel_t> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == std::counted_iterator(iter, 8));
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)),
-                       std::ranges::subrange<
-                         std::counted_iterator<bidirectional_iterator<int*>>,
-                         std::default_sentinel_t>);
-    }
-    {
-      output_iterator<const int*> iter(buffer);
-      std::ranges::subrange<
-        std::counted_iterator<output_iterator<const int*>>,
-        std::default_sentinel_t> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == std::counted_iterator(iter, 8));
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)),
-                       std::ranges::subrange<
-                         std::counted_iterator<output_iterator<const int*>>,
-                         std::default_sentinel_t>);
-    }
-    {
-      const output_iterator<const int*> iter(buffer);
-      std::ranges::subrange<
-        std::counted_iterator<output_iterator<const int*>>,
-        std::default_sentinel_t> s = std::views::counted(iter, 8);
-      assert(s.size() == 8);
-      assert(s.begin() == std::counted_iterator(iter, 8));
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(iter, 8)),
-                       std::ranges::subrange<
-                         std::counted_iterator<output_iterator<const int*>>,
-                         std::default_sentinel_t>);
-    }
-    {
-      cpp20_input_iterator<int*> iter(buffer);
-      std::ranges::subrange<
-        std::counted_iterator<cpp20_input_iterator<int*>>,
-        std::default_sentinel_t> s = std::views::counted(std::move(iter), 8);
-      assert(s.size() == 8);
-      assert(s.begin().base().base() == buffer);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(std::move(iter), 8)),
-                       std::ranges::subrange<
-                         std::counted_iterator<cpp20_input_iterator<int*>>,
-                         std::default_sentinel_t>);
-    }
-    {
-      std::ranges::subrange<
-        std::counted_iterator<cpp20_input_iterator<int*>>,
-        std::default_sentinel_t> s = std::views::counted(cpp20_input_iterator<int*>(buffer), 8);
-      assert(s.size() == 8);
-      assert(s.begin().base().base() == buffer);
-
-      ASSERT_SAME_TYPE(decltype(std::views::counted(cpp20_input_iterator<int*>(buffer), 8)),
-                       std::ranges::subrange<
-                         std::counted_iterator<cpp20_input_iterator<int*>>,
-                         std::default_sentinel_t>);
-    }
+    auto it = cpp17_input_iterator<int*>(buffer);
+
+    auto c1 = std::views::counted(it, 3);
+    auto c2 = std::views::counted(std::as_const(it), 3);
+    auto c3 = std::views::counted(std::move(it), 3);
+    auto c4 = std::views::counted(cpp17_input_iterator<int*>(buffer), 3);
+
+    using Expected = std::ranges::subrange<std::counted_iterator<decltype(it)>, std::default_sentinel_t>;
+
+    ASSERT_SAME_TYPE(decltype(c1), Expected);
+    ASSERT_SAME_TYPE(decltype(c2), Expected);
+    ASSERT_SAME_TYPE(decltype(c3), Expected);
+    ASSERT_SAME_TYPE(decltype(c4), Expected);
+
+    assert(base(c1.begin().base()) == buffer && c1.size() == 3);
+    assert(base(c2.begin().base()) == buffer && c2.size() == 3);
+    assert(base(c3.begin().base()) == buffer && c3.size() == 3);
+    assert(base(c4.begin().base()) == buffer && c4.size() == 3);
   }
 
   {
-    static_assert(std::same_as<decltype(std::views::counted), decltype(std::ranges::views::counted)>);
+    auto it = cpp20_input_iterator<int*>(buffer);
+
+    static_assert(!std::copyable<cpp20_input_iterator<int*>>);
+    static_assert(!CountedInvocable<cpp20_input_iterator<int*>&, int>);
+    static_assert(!CountedInvocable<const cpp20_input_iterator<int*>&, int>);
+    auto c3 = std::views::counted(std::move(it), 3);
+    auto c4 = std::views::counted(cpp20_input_iterator<int*>(buffer), 3);
+
+    using Expected = std::ranges::subrange<std::counted_iterator<decltype(it)>, std::default_sentinel_t>;
+
+    ASSERT_SAME_TYPE(decltype(c3), Expected);
+    ASSERT_SAME_TYPE(decltype(c4), Expected);
+
+    assert(base(c3.begin().base()) == buffer && c3.size() == 3);
+    assert(base(c4.begin().base()) == buffer && c4.size() == 3);
   }
 
   return true;
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
@@ -657,6 +657,8 @@
 
     constexpr I base() && { return std::move(base_); }
 
+    friend constexpr I base(const cpp20_input_iterator& i) { return i.base_; }
+
     template <class T>
     void operator,(T const &) = delete;