diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1207,6 +1207,17 @@
 #    define _LIBCPP_PACKED
 #  endif
 
+// There are a handful of standard library types that are intended to support CTAD but don't need any
+// explicit deduction guides to do so. This macro is used to mark them as such, which suppresses the
+// '-Wctad-maybe-unsupported' compiler warning when CTAD is used in user code with these classes.
+#if _LIBCPP_STD_VER >= 17
+#  define _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(_ClassName)                                                                  \
+    template <class _Tag = void>                                                                                       \
+    _ClassName(typename _Tag::__allow_ctad)->_ClassName<void>
+#else
+#  define _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(_ClassName) static_assert(true, "")
+#endif
+
 #endif // __cplusplus
 
 #endif // _LIBCPP___CONFIG
diff --git a/libcxx/include/__functional/default_searcher.h b/libcxx/include/__functional/default_searcher.h
--- a/libcxx/include/__functional/default_searcher.h
+++ b/libcxx/include/__functional/default_searcher.h
@@ -48,6 +48,7 @@
     _ForwardIterator __last_;
     _BinaryPredicate __pred_;
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(default_searcher);
 
 #endif // _LIBCPP_STD_VER > 14
 
diff --git a/libcxx/include/__iterator/back_insert_iterator.h b/libcxx/include/__iterator/back_insert_iterator.h
--- a/libcxx/include/__iterator/back_insert_iterator.h
+++ b/libcxx/include/__iterator/back_insert_iterator.h
@@ -58,6 +58,7 @@
 
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Container* __get_container() const { return container; }
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(back_insert_iterator);
 
 template <class _Container>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
diff --git a/libcxx/include/__iterator/front_insert_iterator.h b/libcxx/include/__iterator/front_insert_iterator.h
--- a/libcxx/include/__iterator/front_insert_iterator.h
+++ b/libcxx/include/__iterator/front_insert_iterator.h
@@ -56,6 +56,7 @@
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 front_insert_iterator& operator++()    {return *this;}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 front_insert_iterator  operator++(int) {return *this;}
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(front_insert_iterator);
 
 template <class _Container>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
diff --git a/libcxx/include/__iterator/move_iterator.h b/libcxx/include/__iterator/move_iterator.h
--- a/libcxx/include/__iterator/move_iterator.h
+++ b/libcxx/include/__iterator/move_iterator.h
@@ -222,6 +222,7 @@
 
     _Iter __current_;
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(move_iterator);
 
 template <class _Iter1, class _Iter2>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17
diff --git a/libcxx/include/__mutex_base b/libcxx/include/__mutex_base
--- a/libcxx/include/__mutex_base
+++ b/libcxx/include/__mutex_base
@@ -103,6 +103,7 @@
     lock_guard(lock_guard const&) = delete;
     lock_guard& operator=(lock_guard const&) = delete;
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(lock_guard);
 
 template <class _Mutex>
 class _LIBCPP_TEMPLATE_VIS unique_lock
@@ -195,6 +196,7 @@
     _LIBCPP_INLINE_VISIBILITY
     mutex_type* mutex() const _NOEXCEPT {return __m_;}
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(unique_lock);
 
 template <class _Mutex>
 void
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -542,6 +542,7 @@
 
     _MutexTuple __t_;
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(scoped_lock);
 
 #endif // _LIBCPP_STD_VER > 14
 #endif // !_LIBCPP_HAS_NO_THREADS
diff --git a/libcxx/include/shared_mutex b/libcxx/include/shared_mutex
--- a/libcxx/include/shared_mutex
+++ b/libcxx/include/shared_mutex
@@ -432,6 +432,7 @@
     _LIBCPP_INLINE_VISIBILITY
     mutex_type* mutex() const _NOEXCEPT {return __m_;}
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(shared_lock);
 
 template <class _Mutex>
 void
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -726,6 +726,7 @@
     const   value_type* __data_;
     size_type           __size_;
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_string_view);
 
 #if _LIBCPP_STD_VER > 17
 template <class _CharT, class _Traits>
diff --git a/libcxx/test/std/iterators/predef.iterators/insert.iterators/back.insert.iterator/implicit_ctad.pass.cpp b/libcxx/test/std/iterators/predef.iterators/insert.iterators/back.insert.iterator/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/insert.iterators/back.insert.iterator/implicit_ctad.pass.cpp
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// 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++98, c++03, c++11, c++14
+
+// <iterator>
+
+// back_insert_iterator
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <iterator>
+#include <string>
+#include <vector>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  {
+    std::string s;
+    std::back_insert_iterator it(s);
+    ASSERT_SAME_TYPE(decltype(it), std::back_insert_iterator<std::string>);
+  }
+  {
+    std::vector<int> v;
+    std::back_insert_iterator it(v);
+    std::back_insert_iterator copy(it);
+    ASSERT_SAME_TYPE(decltype(it), std::back_insert_iterator<std::vector<int>>);
+    ASSERT_SAME_TYPE(decltype(copy), std::back_insert_iterator<std::vector<int>>);
+  }
+
+  return 0;
+}
diff --git a/libcxx/test/std/iterators/predef.iterators/insert.iterators/front.insert.iterator/implicit_ctad.pass.cpp b/libcxx/test/std/iterators/predef.iterators/insert.iterators/front.insert.iterator/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/insert.iterators/front.insert.iterator/implicit_ctad.pass.cpp
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// 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++98, c++03, c++11, c++14
+
+// <iterator>
+
+// front_insert_iterator
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <deque>
+#include <iterator>
+#include <string>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  {
+    std::string s;
+    std::front_insert_iterator it(s);
+    ASSERT_SAME_TYPE(decltype(it), std::front_insert_iterator<std::string>);
+  }
+  {
+    std::deque<int> v;
+    std::front_insert_iterator it(v);
+    std::front_insert_iterator copy(it);
+    ASSERT_SAME_TYPE(decltype(it), std::front_insert_iterator<std::deque<int>>);
+    ASSERT_SAME_TYPE(decltype(copy), std::front_insert_iterator<std::deque<int>>);
+  }
+
+  return 0;
+}
diff --git a/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/implicit_ctad.pass.cpp b/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/implicit_ctad.pass.cpp
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// 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++98, c++03, c++11, c++14
+
+// <iterator>
+
+// move_iterator
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <iterator>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  int* it = nullptr;
+  std::move_iterator move_it(it);
+  ASSERT_SAME_TYPE(decltype(move_it), std::move_iterator<int*>);
+
+  return 0;
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.deduct/implicit.pass.cpp b/libcxx/test/std/strings/string.view/string.view.deduct/implicit.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.deduct/implicit.pass.cpp
@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// 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++98, c++03, c++11, c++14
+
+// <string_view>
+
+// basic_string_view
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <string_view>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  {
+    char const* str = "hello world";
+    std::basic_string_view sv(str);
+    ASSERT_SAME_TYPE(decltype(sv), std::basic_string_view<char>);
+  }
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+  {
+    wchar_t const* str = L"hello world";
+    std::basic_string_view sv(str);
+    ASSERT_SAME_TYPE(decltype(sv), std::basic_string_view<wchar_t>);
+  }
+#endif
+
+  return 0;
+}
diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/implicit_ctad.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/implicit_ctad.pass.cpp
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: no-threads
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <mutex>
+
+// lock_guard
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <mutex>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  std::mutex mutex;
+  {
+    std::lock_guard lock(mutex);
+    ASSERT_SAME_TYPE(decltype(lock), std::lock_guard<std::mutex>);
+  }
+
+  return 0;
+}
+
diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/implicit_ctad.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.scoped/implicit_ctad.pass.cpp
@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: no-threads
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <mutex>
+
+// scoped_lock
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <mutex>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  std::mutex m1;
+  std::recursive_mutex m2;
+  std::recursive_timed_mutex m3;
+  {
+    std::scoped_lock lock(m1);
+    ASSERT_SAME_TYPE(decltype(lock), std::scoped_lock<std::mutex>);
+  }
+  {
+    std::scoped_lock lock(m1, m2);
+    ASSERT_SAME_TYPE(decltype(lock), std::scoped_lock<std::mutex, std::recursive_mutex>);
+  }
+  {
+    std::scoped_lock lock(m1, m2, m3);
+    ASSERT_SAME_TYPE(decltype(lock), std::scoped_lock<std::mutex, std::recursive_mutex, std::recursive_timed_mutex>);
+  }
+
+  return 0;
+}
+
diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/implicit_ctad.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/implicit_ctad.pass.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: no-threads
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <shared_mutex>
+
+// shared_lock
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <shared_mutex>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  std::shared_mutex mutex;
+  {
+    std::shared_lock lock(mutex);
+    ASSERT_SAME_TYPE(decltype(lock), std::shared_lock<std::shared_mutex>);
+  }
+
+  return 0;
+}
diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.unique/implicit_ctad.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.unique/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.unique/implicit_ctad.pass.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: no-threads
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <mutex>
+
+// unique_lock
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <mutex>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  std::mutex mutex;
+  {
+    std::unique_lock lock(mutex);
+    ASSERT_SAME_TYPE(decltype(lock), std::unique_lock<std::mutex>);
+  }
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/func.search/func.search.default/implicit_ctad.pass.cpp b/libcxx/test/std/utilities/function.objects/func.search/func.search.default/implicit_ctad.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/func.search/func.search.default/implicit_ctad.pass.cpp
@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// 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++98, c++03, c++11, c++14
+
+// <functional>
+
+// default searcher
+
+// Make sure that the implicitly-generated CTAD works.
+
+#include <functional>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  {
+    char const* str = "hello";
+    std::default_searcher searcher(str, str + 3);
+    ASSERT_SAME_TYPE(decltype(searcher), std::default_searcher<char const*, std::equal_to<>>);
+  }
+  {
+    char const* str = "hello";
+    std::default_searcher searcher(str, str + 3, std::not_equal_to<>());
+    ASSERT_SAME_TYPE(decltype(searcher), std::default_searcher<char const*, std::not_equal_to<>>);
+  }
+
+  return 0;
+}
diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -13,6 +13,7 @@
 _warningFlags = [
   '-Werror',
   '-Wall',
+  '-Wctad-maybe-unsupported',
   '-Wextra',
   '-Wshadow',
   '-Wundef',