Index: libcxx/include/compare
===================================================================
--- libcxx/include/compare
+++ libcxx/include/compare
@@ -248,6 +248,8 @@
   _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(partial_ordering, partial_ordering) noexcept = default;
+
   _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
   _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
 #endif
@@ -364,6 +366,8 @@
   _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_ordering, weak_ordering) noexcept = default;
+
   _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
   _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
 #endif
@@ -490,6 +494,8 @@
   _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_ordering, strong_ordering) noexcept = default;
+
   _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
   _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
 #endif
Index: libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
===================================================================
--- libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
+++ libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
@@ -150,6 +150,42 @@
       break;
     }
   }
+  {
+    static_assert(std::partial_ordering::less == std::partial_ordering::less);
+    static_assert(std::partial_ordering::less !=
+                  std::partial_ordering::equivalent);
+    static_assert(std::partial_ordering::less !=
+                  std::partial_ordering::greater);
+    static_assert(std::partial_ordering::less !=
+                  std::partial_ordering::unordered);
+
+    static_assert(std::partial_ordering::equivalent !=
+                  std::partial_ordering::less);
+    static_assert(std::partial_ordering::equivalent ==
+                  std::partial_ordering::equivalent);
+    static_assert(std::partial_ordering::equivalent !=
+                  std::partial_ordering::greater);
+    static_assert(std::partial_ordering::equivalent !=
+                  std::partial_ordering::unordered);
+
+    static_assert(std::partial_ordering::greater !=
+                  std::partial_ordering::less);
+    static_assert(std::partial_ordering::greater !=
+                  std::partial_ordering::equivalent);
+    static_assert(std::partial_ordering::greater ==
+                  std::partial_ordering::greater);
+    static_assert(std::partial_ordering::greater !=
+                  std::partial_ordering::unordered);
+
+    static_assert(std::partial_ordering::unordered !=
+                  std::partial_ordering::less);
+    static_assert(std::partial_ordering::unordered !=
+                  std::partial_ordering::equivalent);
+    static_assert(std::partial_ordering::unordered !=
+                  std::partial_ordering::greater);
+    static_assert(std::partial_ordering::unordered ==
+                  std::partial_ordering::unordered);
+  }
 #endif
 
   return true;
Index: libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
===================================================================
--- libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
+++ libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
@@ -198,6 +198,20 @@
       break;
     }
   }
+  {
+    static_assert(std::strong_ordering::less == std::strong_ordering::less);
+    static_assert(std::strong_ordering::less != std::strong_ordering::equal);
+    static_assert(std::strong_ordering::less != std::strong_ordering::greater);
+
+    static_assert(std::strong_ordering::equal != std::strong_ordering::less);
+    static_assert(std::strong_ordering::equal == std::strong_ordering::equal);
+    static_assert(std::strong_ordering::equal != std::strong_ordering::greater);
+
+    static_assert(std::strong_ordering::greater != std::strong_ordering::less);
+    static_assert(std::strong_ordering::greater != std::strong_ordering::equal);
+    static_assert(std::strong_ordering::greater ==
+                  std::strong_ordering::greater);
+  }
 #endif
 
   return true;
Index: libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
===================================================================
--- libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
+++ libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
@@ -155,6 +155,23 @@
       break;
     }
   }
+
+  {
+    static_assert(std::weak_ordering::less == std::weak_ordering::less);
+    static_assert(std::weak_ordering::less != std::weak_ordering::equivalent);
+    static_assert(std::weak_ordering::less != std::weak_ordering::greater);
+
+    static_assert(std::weak_ordering::equivalent != std::weak_ordering::less);
+    static_assert(std::weak_ordering::equivalent ==
+                  std::weak_ordering::equivalent);
+    static_assert(std::weak_ordering::equivalent !=
+                  std::weak_ordering::greater);
+
+    static_assert(std::weak_ordering::greater != std::weak_ordering::less);
+    static_assert(std::weak_ordering::greater !=
+                  std::weak_ordering::equivalent);
+    static_assert(std::weak_ordering::greater == std::weak_ordering::greater);
+  }
 #endif
 
   return true;