diff --git a/libcxx/include/stack b/libcxx/include/stack
--- a/libcxx/include/stack
+++ b/libcxx/include/stack
@@ -89,6 +89,9 @@
   bool operator>=(const stack<T, Container>& x, const stack<T, Container>& y);
 template <class T, class Container>
   bool operator<=(const stack<T, Container>& x, const stack<T, Container>& y);
+template<class T, three_way_comparable Container>
+  compare_three_way_result_t<Container>
+    operator<=>(const stack<T, Container>& x, const stack<T, Container>& y); // since C++20
 
 template <class T, class Container>
   void swap(stack<T, Container>& x, stack<T, Container>& y)
@@ -346,6 +349,16 @@
     return !(__y < __x);
 }
 
+#if _LIBCPP_STD_VER >= 20
+
+template <class _Tp, three_way_comparable _Container>
+_LIBCPP_HIDE_FROM_ABI compare_three_way_result_t<_Container>
+operator<=>(const stack<_Tp, _Container>& __x, const stack<_Tp, _Container>& __y) {
+    return __x.__get_container() <=> __y.__get_container();
+}
+
+#endif
+
 template <class _Tp, class _Container>
 inline _LIBCPP_INLINE_VISIBILITY
 __enable_if_t<__is_swappable<_Container>::value, void>
diff --git a/libcxx/test/std/containers/container.adaptors/stack/compare.three_way.pass.cpp b/libcxx/test/std/containers/container.adaptors/stack/compare.three_way.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/containers/container.adaptors/stack/compare.three_way.pass.cpp
@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <stack>
+
+// template<class T, three_way_comparable Container>
+//   compare_three_way_result_t<Container>
+//     operator<=>(const stack<T, Container>& x, const stack<T, Container>& y);
+
+#include <cassert>
+#include <deque>
+#include <list>
+#include <stack>
+#include <vector>
+
+#include "nasty_containers.h"
+#include "test_container_comparisons.h"
+
+int main(int, char**) {
+  assert((test_ordered_container_adaptor_spaceship<std::stack, std::deque>()));
+  assert((test_ordered_container_adaptor_spaceship<std::stack, std::list>()));
+  assert((test_ordered_container_adaptor_spaceship<std::stack, std::vector>()));
+  assert((test_sequence_container_adaptor_spaceship<std::stack, nasty_list>()));
+  assert((test_sequence_container_adaptor_spaceship<std::stack, nasty_vector>()));
+  // `std::stack` is not constexpr, so no `static_assert` test here.
+  return 0;
+}