diff --git a/libcxx/include/__availability b/libcxx/include/__availability
--- a/libcxx/include/__availability
+++ b/libcxx/include/__availability
@@ -172,6 +172,8 @@
     // be avoided.
 // #   define _LIBCPP_HAS_NO_VERBOSE_ABORT_IN_LIBRARY
 
+#  define _LIBCPP_AVAILABILITY_MEMORY_RESOURCE
+
 #elif defined(__APPLE__)
 
 #   define _LIBCPP_AVAILABILITY_SHARED_MUTEX                                    \
@@ -273,6 +275,8 @@
 
 #   define _LIBCPP_HAS_NO_VERBOSE_ABORT_IN_LIBRARY
 
+#  define _LIBCPP_AVAILABILITY_MEMORY_RESOURCE __attribute__((__unavailable__))
+
 #else
 
 // ...New vendors can add availability markup here...
diff --git a/libcxx/include/__memory_resource/memory_resource.h b/libcxx/include/__memory_resource/memory_resource.h
--- a/libcxx/include/__memory_resource/memory_resource.h
+++ b/libcxx/include/__memory_resource/memory_resource.h
@@ -61,13 +61,10 @@
 
 // [mem.res.global]
 
-_LIBCPP_FUNC_VIS memory_resource* get_default_resource() noexcept;
-
-_LIBCPP_FUNC_VIS memory_resource* set_default_resource(memory_resource*) noexcept;
-
-_LIBCPP_FUNC_VIS memory_resource* new_delete_resource() noexcept;
-
-_LIBCPP_FUNC_VIS memory_resource* null_memory_resource() noexcept;
+_LIBCPP_AVAILABILITY_MEMORY_RESOURCE _LIBCPP_FUNC_VIS memory_resource* get_default_resource() noexcept;
+_LIBCPP_AVAILABILITY_MEMORY_RESOURCE _LIBCPP_FUNC_VIS memory_resource* set_default_resource(memory_resource*) noexcept;
+_LIBCPP_AVAILABILITY_MEMORY_RESOURCE _LIBCPP_FUNC_VIS memory_resource* new_delete_resource() noexcept;
+_LIBCPP_AVAILABILITY_MEMORY_RESOURCE _LIBCPP_FUNC_VIS memory_resource* null_memory_resource() noexcept;
 
 } // namespace pmr
 
diff --git a/libcxx/include/__memory_resource/monotonic_buffer_resource.h b/libcxx/include/__memory_resource/monotonic_buffer_resource.h
--- a/libcxx/include/__memory_resource/monotonic_buffer_resource.h
+++ b/libcxx/include/__memory_resource/monotonic_buffer_resource.h
@@ -96,7 +96,7 @@
   _LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; }
 
 protected:
-  void* do_allocate(size_t __bytes, size_t __alignment) override; // key function
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE void* do_allocate(size_t __bytes, size_t __alignment) override; // key function
 
   _LIBCPP_HIDE_FROM_ABI void do_deallocate(void*, size_t, size_t) override {}
 
diff --git a/libcxx/include/__memory_resource/synchronized_pool_resource.h b/libcxx/include/__memory_resource/synchronized_pool_resource.h
--- a/libcxx/include/__memory_resource/synchronized_pool_resource.h
+++ b/libcxx/include/__memory_resource/synchronized_pool_resource.h
@@ -76,7 +76,8 @@
     return __unsync_.deallocate(__p, __bytes, __align);
   }
 
-  bool do_is_equal(const memory_resource& __other) const noexcept override; // key function
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE bool
+  do_is_equal(const memory_resource& __other) const noexcept override; // key function
 
 private:
 #  if !defined(_LIBCPP_HAS_NO_THREADS)
diff --git a/libcxx/include/__memory_resource/unsynchronized_pool_resource.h b/libcxx/include/__memory_resource/unsynchronized_pool_resource.h
--- a/libcxx/include/__memory_resource/unsynchronized_pool_resource.h
+++ b/libcxx/include/__memory_resource/unsynchronized_pool_resource.h
@@ -57,6 +57,7 @@
   int __pool_index(size_t __bytes, size_t __align) const;
 
 public:
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE
   unsynchronized_pool_resource(const pool_options& __opts, memory_resource* __upstream);
 
   _LIBCPP_HIDE_FROM_ABI unsynchronized_pool_resource()
@@ -74,16 +75,16 @@
 
   unsynchronized_pool_resource& operator=(const unsynchronized_pool_resource&) = delete;
 
-  void release();
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE void release();
 
   _LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; }
 
-  pool_options options() const;
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE pool_options options() const;
 
 protected:
-  void* do_allocate(size_t __bytes, size_t __align) override; // key function
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE void* do_allocate(size_t __bytes, size_t __align) override; // key function
 
-  void do_deallocate(void* __p, size_t __bytes, size_t __align) override;
+  _LIBCPP_AVAILABILITY_MEMORY_RESOURCE void do_deallocate(void* __p, size_t __bytes, size_t __align) override;
 
   _LIBCPP_HIDE_FROM_ABI bool do_is_equal(const memory_resource& __other) const _NOEXCEPT override {
     return &__other == this;
diff --git a/libcxx/test/libcxx/mem/mem.res/availability.verify.cpp b/libcxx/test/libcxx/mem/mem.res/availability.verify.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/mem/mem.res/availability.verify.cpp
@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// REQUIRES: (use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14|15}}) || (use_system_cxx_lib && target={{.+}}-apple-macosx{{11.0|12.0}})
+
+#include <memory_resource>
+
+struct SyncMemRes : std::pmr::synchronized_pool_resource {
+  bool do_is_equal(const std::pmr::memory_resource& other) const noexcept override {
+    return std::pmr::synchronized_pool_resource::do_is_equal(other); // expected-error {{is unavailable}}
+  }
+};
+
+struct MonotonicMemRes : std::pmr::monotonic_buffer_resource {
+  void* do_allocate(size_t bytes, size_t alignment) override {
+    return std::pmr::monotonic_buffer_resource::do_allocate(bytes, alignment); // expected-error {{is unavailable}}
+  }
+};
+
+struct UnsyncMemRes : std::pmr::unsynchronized_pool_resource {
+  void* do_allocate(size_t bytes, size_t alignment) override {
+    return std::pmr::unsynchronized_pool_resource::do_allocate(bytes, alignment); // expected-error {{is unavailable}}
+  }
+
+  void do_deallocate(void* ptr, size_t bytes, size_t alignment) override {
+    return std::pmr::unsynchronized_pool_resource::do_deallocate(ptr, bytes, alignment);
+  }
+};
+
+void functions() {
+  std::pmr::get_default_resource();        // expected-error {{is unavailable}}
+  std::pmr::set_default_resource(nullptr); // expected-error {{is unavailable}}
+  std::pmr::new_delete_resource();         // expected-error {{is unavailable}}
+  std::pmr::null_memory_resource();        // expected-error {{is unavailable}}
+}
+
+void unsynchronized_pool_resource() {
+  std::pmr::unsynchronized_pool_resource res(std::pmr::pool_options{}, nullptr); // expected-error {{is unavailable}}
+  res.release();                                                                 // expected-error {{is unavailable}}
+  res.options();                                                                 // expected-error {{is unavailable}}
+}