diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -103,7 +103,6 @@
__format/format_error.h
__format/format_parse_context.h
__function_like.h
- __functional_base
__functional/binary_function.h
__functional/binary_negate.h
__functional/bind_front.h
diff --git a/libcxx/include/__functional/bind.h b/libcxx/include/__functional/bind.h
--- a/libcxx/include/__functional/bind.h
+++ b/libcxx/include/__functional/bind.h
@@ -17,6 +17,7 @@
#include <cstddef>
#include <tuple>
#include <type_traits>
+#include <typeinfo>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
diff --git a/libcxx/include/__functional_base b/libcxx/include/__functional_base
deleted file mode 100644
--- a/libcxx/include/__functional_base
+++ /dev/null
@@ -1,31 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP_FUNCTIONAL_BASE
-#define _LIBCPP_FUNCTIONAL_BASE
-
-#include <__config>
-#include <__functional/binary_function.h>
-#include <__functional/invoke.h>
-#include <__functional/operations.h>
-#include <__functional/reference_wrapper.h>
-#include <__functional/unary_function.h>
-#include <__functional/weak_result_type.h>
-#include <__memory/allocator_arg_t.h>
-#include <__memory/uses_allocator.h>
-#include <exception>
-#include <new>
-#include <type_traits>
-#include <typeinfo>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#pragma GCC system_header
-#endif
-
-#endif // _LIBCPP_FUNCTIONAL_BASE
diff --git a/libcxx/include/__hash_table b/libcxx/include/__hash_table
--- a/libcxx/include/__hash_table
+++ b/libcxx/include/__hash_table
@@ -13,6 +13,7 @@
#include <__bits> // __libcpp_clz
#include <__config>
#include <__debug>
+#include <__functional/hash.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <__utility/pair.h>
diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -12,7 +12,6 @@
#include <__availability>
#include <__config>
-#include <__functional_base>
#include <__functional/binary_function.h>
#include <__functional/operations.h>
#include <__functional/reference_wrapper.h>
diff --git a/libcxx/include/__memory/unique_ptr.h b/libcxx/include/__memory/unique_ptr.h
--- a/libcxx/include/__memory/unique_ptr.h
+++ b/libcxx/include/__memory/unique_ptr.h
@@ -11,7 +11,6 @@
#define _LIBCPP___MEMORY_UNIQUE_PTR_H
#include <__config>
-#include <__functional_base>
#include <__functional/hash.h>
#include <__functional/operations.h>
#include <__memory/allocator_traits.h> // __pointer
diff --git a/libcxx/include/__ranges/drop_view.h b/libcxx/include/__ranges/drop_view.h
--- a/libcxx/include/__ranges/drop_view.h
+++ b/libcxx/include/__ranges/drop_view.h
@@ -12,6 +12,7 @@
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__iterator/concepts.h>
+#include <__iterator/next.h>
#include <__ranges/access.h>
#include <__ranges/view_interface.h>
#include <__ranges/all.h>
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -650,7 +650,6 @@
#include <__bits> // __libcpp_clz
#include <cstddef>
#include <cstring>
-#include <functional>
#include <initializer_list>
#include <memory>
#include <iterator>
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -114,7 +114,7 @@
#include <__config>
#include <__bit_reference>
-#include <__functional_base>
+#include <__functional/unary_function.h>
#include <climits>
#include <cstddef>
#include <iosfwd>
diff --git a/libcxx/include/concepts b/libcxx/include/concepts
--- a/libcxx/include/concepts
+++ b/libcxx/include/concepts
@@ -131,7 +131,6 @@
#include <__config>
#include <__functional/invoke.h>
-#include <__functional_base>
#include <__utility/declval.h>
#include <__utility/exchange.h>
#include <type_traits>
diff --git a/libcxx/include/experimental/__memory b/libcxx/include/experimental/__memory
--- a/libcxx/include/experimental/__memory
+++ b/libcxx/include/experimental/__memory
@@ -14,7 +14,6 @@
#include <__memory/uses_allocator.h>
#include <experimental/__config>
#include <experimental/utility> // for erased_type
-#include <__functional_base>
#include <type_traits>
_LIBCPP_BEGIN_NAMESPACE_LFTS
diff --git a/libcxx/include/experimental/propagate_const b/libcxx/include/experimental/propagate_const
--- a/libcxx/include/experimental/propagate_const
+++ b/libcxx/include/experimental/propagate_const
@@ -113,8 +113,10 @@
#if _LIBCPP_STD_VER > 11
-#include <type_traits>
+#include <__utility/forward.h>
+#include <__utility/move.h>
#include <functional>
+#include <type_traits>
_LIBCPP_BEGIN_NAMESPACE_LFTS_V2
diff --git a/libcxx/include/ext/hash_map b/libcxx/include/ext/hash_map
--- a/libcxx/include/ext/hash_map
+++ b/libcxx/include/ext/hash_map
@@ -202,9 +202,9 @@
*/
#include <__config>
+#include <__functional/operations.h>
#include <__hash_table>
#include <__utility/pair.h>
-#include <functional>
#include <stdexcept>
#include <type_traits>
#include <ext/__hash>
diff --git a/libcxx/include/ext/hash_set b/libcxx/include/ext/hash_set
--- a/libcxx/include/ext/hash_set
+++ b/libcxx/include/ext/hash_set
@@ -193,9 +193,9 @@
*/
#include <__config>
+#include <__functional/operations.h>
#include <__hash_table>
#include <__utility/pair.h>
-#include <functional>
#include <ext/__hash>
#if defined(__DEPRECATED) && __DEPRECATED
diff --git a/libcxx/include/functional b/libcxx/include/functional
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -487,9 +487,6 @@
*/
-#include <__algorithm/search.h>
-#include <__config>
-#include <__debug>
#include <__functional/binary_function.h> // TODO: deprecate
#include <__functional/binary_negate.h>
#include <__functional/bind_front.h>
@@ -512,13 +509,7 @@
#include <__functional/unary_function.h> // TODO: deprecate
#include <__functional/unary_negate.h>
#include <__functional/unwrap_ref.h>
-#include <__utility/forward.h>
-#include <concepts>
-#include <exception>
-#include <memory>
-#include <tuple>
-#include <type_traits>
-#include <typeinfo>
+
#include <version>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -560,7 +560,6 @@
#include <__config>
#include <__debug>
-#include <__functional_base>
#include <__iterator/advance.h>
#include <__iterator/back_insert_iterator.h>
#include <__iterator/concepts.h>
diff --git a/libcxx/include/map b/libcxx/include/map
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -492,6 +492,8 @@
#include <__config>
#include <__debug>
#include <__functional/is_transparent.h>
+#include <__functional/binary_function.h>
+#include <__functional/operations.h>
#include <__node_handle>
#include <__tree>
#include <__utility/forward.h>
@@ -500,7 +502,6 @@
#include <__utility/piecewise_construct.h>
#include <__utility/swap.h>
#include <compare>
-#include <functional>
#include <initializer_list>
#include <iterator> // __libcpp_erase_if_container
#include <memory>
diff --git a/libcxx/include/memory b/libcxx/include/memory
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -668,7 +668,6 @@
*/
#include <__config>
-#include <__functional_base>
#include <__memory/addressof.h>
#include <__memory/allocation_guard.h>
#include <__memory/allocator.h>
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -411,7 +411,11 @@
module __functional {
module binary_function { header "__functional/binary_function.h" }
module binary_negate { header "__functional/binary_negate.h" }
- module bind { header "__functional/bind.h" }
+ module bind {
+ export typeinfo // TODO: investigate whether this is necessary or a hack
+ // (requires in-depth knowledge of `std::bind`)
+ header "__functional/bind.h"
+ }
module bind_front { header "__functional/bind_front.h" }
module binder1st { header "__functional/binder1st.h" }
module binder2nd { header "__functional/binder2nd.h" }
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -192,7 +192,6 @@
#include <__utility/forward.h>
#include <__utility/move.h>
#include <cstdint>
-#include <functional>
#include <memory>
#ifndef _LIBCPP_CXX03_LANG
# include <tuple>
diff --git a/libcxx/include/numeric b/libcxx/include/numeric
--- a/libcxx/include/numeric
+++ b/libcxx/include/numeric
@@ -146,9 +146,9 @@
#include <__config>
#include <__debug>
+#include <__functional/operations.h>
#include <__utility/move.h>
#include <cmath> // for isnormal
-#include <functional>
#include <iterator>
#include <limits> // for numeric_limits
#include <version>
diff --git a/libcxx/include/optional b/libcxx/include/optional
--- a/libcxx/include/optional
+++ b/libcxx/include/optional
@@ -149,14 +149,15 @@
#include <__availability>
#include <__config>
#include <__debug>
-#include <__functional_base>
+#include <__functional/hash.h>
+#include <__memory/construct_at.h>
+#include <__tuple>
#include <__utility/declval.h>
#include <__utility/forward.h>
#include <__utility/in_place.h>
#include <__utility/move.h>
#include <__utility/swap.h>
#include <compare>
-#include <functional>
#include <initializer_list>
#include <new>
#include <stdexcept>
diff --git a/libcxx/include/queue b/libcxx/include/queue
--- a/libcxx/include/queue
+++ b/libcxx/include/queue
@@ -179,6 +179,8 @@
*/
#include <__config>
+#include <__functional/binary_function.h>
+#include <__functional/operations.h>
#include <__memory/uses_allocator.h>
#include <__utility/forward.h>
#include <__utility/move.h>
@@ -186,7 +188,6 @@
#include <algorithm>
#include <compare>
#include <deque>
-#include <functional>
#include <vector>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/set b/libcxx/include/set
--- a/libcxx/include/set
+++ b/libcxx/include/set
@@ -436,13 +436,13 @@
#include <__config>
#include <__debug>
#include <__functional/is_transparent.h>
+#include <__functional/operations.h>
#include <__node_handle>
#include <__tree>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <__utility/pair.h>
#include <compare>
-#include <functional>
#include <initializer_list>
#include <iterator> // __libcpp_erase_if_container
#include <version>
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -515,7 +515,8 @@
#include <__config>
#include <__debug>
-#include <__functional_base>
+#include <__functional/hash.h>
+#include <__functional/unary_function.h>
#include <__iterator/wrap_iter.h>
#include <__utility/move.h>
#include <algorithm>
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -186,6 +186,8 @@
#include <__config>
#include <__debug>
+#include <__functional/hash.h>
+#include <__functional/unary_function.h>
#include <__ranges/enable_borrowed_range.h>
#include <__ranges/enable_view.h>
#include <__string>
diff --git a/libcxx/include/system_error b/libcxx/include/system_error
--- a/libcxx/include/system_error
+++ b/libcxx/include/system_error
@@ -145,7 +145,6 @@
#include <__config>
#include <__errc>
#include <__functional/unary_function.h>
-#include <__functional_base>
#include <compare>
#include <stdexcept>
#include <string>
diff --git a/libcxx/include/thread b/libcxx/include/thread
--- a/libcxx/include/thread
+++ b/libcxx/include/thread
@@ -84,7 +84,6 @@
#include <__config>
#include <__debug>
-#include <__functional_base>
#include <__mutex_base>
#include <__threading_support>
#include <__utility/__decay_copy.h>
@@ -92,7 +91,6 @@
#include <__utility/move.h>
#include <chrono>
#include <cstddef>
-#include <functional>
#include <iosfwd>
#include <memory>
#include <system_error>
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -151,7 +151,6 @@
#include <__config>
#include <__functional/unwrap_ref.h>
-#include <__functional_base>
#include <__memory/allocator_arg_t.h>
#include <__memory/uses_allocator.h>
#include <__tuple>
@@ -160,6 +159,7 @@
#include <__utility/move.h>
#include <__utility/pair.h>
#include <__utility/piecewise_construct.h>
+#include <__utility/swap.h>
#include <compare>
#include <cstddef>
#include <type_traits>
diff --git a/libcxx/include/typeindex b/libcxx/include/typeindex
--- a/libcxx/include/typeindex
+++ b/libcxx/include/typeindex
@@ -46,7 +46,6 @@
#include <__config>
#include <__functional/unary_function.h>
-#include <__functional_base>
#include <compare>
#include <typeinfo>
diff --git a/libcxx/include/unordered_map b/libcxx/include/unordered_map
--- a/libcxx/include/unordered_map
+++ b/libcxx/include/unordered_map
@@ -433,7 +433,9 @@
#include <__config>
#include <__debug>
+#include <__functional/hash.h>
#include <__functional/is_transparent.h>
+#include <__functional/operations.h>
#include <__hash_table>
#include <__node_handle>
#include <__utility/forward.h>
@@ -441,7 +443,6 @@
#include <__utility/pair.h>
#include <__utility/piecewise_construct.h>
#include <compare>
-#include <functional>
#include <iterator> // __libcpp_erase_if_container
#include <stdexcept>
#include <tuple>
diff --git a/libcxx/include/unordered_set b/libcxx/include/unordered_set
--- a/libcxx/include/unordered_set
+++ b/libcxx/include/unordered_set
@@ -388,7 +388,9 @@
#include <__config>
#include <__debug>
+#include <__functional/hash.h>
#include <__functional/is_transparent.h>
+#include <__functional/operations.h>
#include <__hash_table>
#include <__node_handle>
#include <__utility/declval.h>
@@ -396,7 +398,6 @@
#include <__utility/pair.h>
#include <__utility/move.h>
#include <compare>
-#include <functional>
#include <iterator> // __libcpp_erase_if_container
#include <version>
diff --git a/libcxx/include/valarray b/libcxx/include/valarray
--- a/libcxx/include/valarray
+++ b/libcxx/include/valarray
@@ -340,10 +340,10 @@
*/
#include <__config>
+#include <__functional/operations.h>
#include <algorithm>
#include <cmath>
#include <cstddef>
-#include <functional>
#include <initializer_list>
#include <new>
diff --git a/libcxx/include/variant b/libcxx/include/variant
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -201,6 +201,9 @@
#include <__availability>
#include <__config>
+#include <__functional/hash.h>
+#include <__functional/operations.h>
+#include <__functional/unary_function.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
#include <__utility/in_place.h>
@@ -210,7 +213,6 @@
#include <array>
#include <compare>
#include <exception>
-#include <functional>
#include <initializer_list>
#include <limits>
#include <new>
diff --git a/libcxx/include/vector b/libcxx/include/vector
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -274,7 +274,8 @@
#include <__config>
#include <__bit_reference>
#include <__debug>
-#include <__functional_base>
+#include <__functional/hash.h>
+#include <__functional/unary_function.h>
#include <__iterator/wrap_iter.h>
#include <__split_buffer>
#include <__utility/forward.h>
diff --git a/libcxx/test/libcxx/depr/depr.function.objects/depr.adaptors.cxx1z.pass.cpp b/libcxx/test/libcxx/depr/depr.function.objects/depr.adaptors.cxx1z.pass.cpp
--- a/libcxx/test/libcxx/depr/depr.function.objects/depr.adaptors.cxx1z.pass.cpp
+++ b/libcxx/test/libcxx/depr/depr.function.objects/depr.adaptors.cxx1z.pass.cpp
@@ -18,6 +18,7 @@
#include <functional>
#include <cassert>
+#include <type_traits>
#include "test_macros.h"
diff --git a/libcxx/test/libcxx/numerics/numeric.ops/midpoint.integer.pass.cpp b/libcxx/test/libcxx/numerics/numeric.ops/midpoint.integer.pass.cpp
--- a/libcxx/test/libcxx/numerics/numeric.ops/midpoint.integer.pass.cpp
+++ b/libcxx/test/libcxx/numerics/numeric.ops/midpoint.integer.pass.cpp
@@ -15,6 +15,7 @@
#include <numeric>
#include <cassert>
+#include <cstdint>
#include "test_macros.h"
// Users are not supposed to provide template argument lists for
diff --git a/libcxx/test/libcxx/utilities/function.objects/func.require/bullet_4_5_6.pass.cpp b/libcxx/test/libcxx/utilities/function.objects/func.require/bullet_4_5_6.pass.cpp
--- a/libcxx/test/libcxx/utilities/function.objects/func.require/bullet_4_5_6.pass.cpp
+++ b/libcxx/test/libcxx/utilities/function.objects/func.require/bullet_4_5_6.pass.cpp
@@ -40,6 +40,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "invoke_helpers.h"
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
@@ -16,6 +16,7 @@
#include <algorithm>
#include <cassert>
+#include <functional>
#include "test_macros.h"
#include "test_iterators.h"
diff --git a/libcxx/test/std/algorithms/alg.sorting/alg.heap.operations/sort.heap/sort_heap_comp.pass.cpp b/libcxx/test/std/algorithms/alg.sorting/alg.heap.operations/sort.heap/sort_heap_comp.pass.cpp
--- a/libcxx/test/std/algorithms/alg.sorting/alg.heap.operations/sort.heap/sort_heap_comp.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.sorting/alg.heap.operations/sort.heap/sort_heap_comp.pass.cpp
@@ -15,6 +15,7 @@
#include <algorithm>
#include <cassert>
+#include <functional>
#include "test_macros.h"
#include "test_iterators.h"
diff --git a/libcxx/test/std/concepts/concepts.callable/concept.invocable/invocable.compile.pass.cpp b/libcxx/test/std/concepts/concepts.callable/concept.invocable/invocable.compile.pass.cpp
--- a/libcxx/test/std/concepts/concepts.callable/concept.invocable/invocable.compile.pass.cpp
+++ b/libcxx/test/std/concepts/concepts.callable/concept.invocable/invocable.compile.pass.cpp
@@ -12,8 +12,10 @@
// template<class T, class U>
// concept invocable;
-#include <chrono>
#include <concepts>
+
+#include <chrono>
+#include <functional>
#include <memory>
#include <random>
#include <type_traits>
diff --git a/libcxx/test/std/concepts/concepts.callable/concept.regularinvocable/regular_invocable.compile.pass.cpp b/libcxx/test/std/concepts/concepts.callable/concept.regularinvocable/regular_invocable.compile.pass.cpp
--- a/libcxx/test/std/concepts/concepts.callable/concept.regularinvocable/regular_invocable.compile.pass.cpp
+++ b/libcxx/test/std/concepts/concepts.callable/concept.regularinvocable/regular_invocable.compile.pass.cpp
@@ -12,8 +12,10 @@
// template<class T, class U>
// concept regular_invocable;
-#include <chrono>
#include <concepts>
+
+#include <chrono>
+#include <functional>
#include <memory>
#include <random>
#include <type_traits>
diff --git a/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.fail.cpp b/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.fail.cpp
--- a/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.fail.cpp
+++ b/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.fail.cpp
@@ -15,6 +15,7 @@
#include <iterator>
#include <cassert>
#include <cstddef>
+#include <functional>
int main(int, char**)
diff --git a/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.pass.cpp b/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.pass.cpp
--- a/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.pass.cpp
+++ b/libcxx/test/std/containers/container.adaptors/priority.queue/priqueue.cons/deduct.pass.cpp
@@ -31,6 +31,7 @@
#include <cassert>
#include <cstddef>
#include <climits> // INT_MAX
+#include <functional>
#include "test_macros.h"
#include "test_iterators.h"
diff --git a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.cons/deduct.pass.cpp b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.cons/deduct.pass.cpp
--- a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.cons/deduct.pass.cpp
+++ b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.cons/deduct.pass.cpp
@@ -19,9 +19,11 @@
#include <forward_list>
#include <iterator>
+#include <algorithm>
#include <cassert>
#include <cstddef>
#include <climits> // INT_MAX
+#include <type_traits>
#include "test_macros.h"
#include "test_iterators.h"
diff --git a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/remove_if.pass.cpp b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/remove_if.pass.cpp
--- a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/remove_if.pass.cpp
+++ b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/remove_if.pass.cpp
@@ -15,6 +15,7 @@
#include <iterator>
#include <cassert>
#include <cstddef>
+#include <functional>
#include "test_macros.h"
#include "min_allocator.h"
diff --git a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/unique_pred.pass.cpp b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/unique_pred.pass.cpp
--- a/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/unique_pred.pass.cpp
+++ b/libcxx/test/std/containers/sequences/forwardlist/forwardlist.ops/unique_pred.pass.cpp
@@ -14,6 +14,7 @@
#include <forward_list>
#include <iterator>
#include <cassert>
+#include <functional>
#include "test_macros.h"
#include "min_allocator.h"
diff --git a/libcxx/test/std/containers/sequences/list/list.ops/unique_pred.pass.cpp b/libcxx/test/std/containers/sequences/list/list.ops/unique_pred.pass.cpp
--- a/libcxx/test/std/containers/sequences/list/list.ops/unique_pred.pass.cpp
+++ b/libcxx/test/std/containers/sequences/list/list.ops/unique_pred.pass.cpp
@@ -13,6 +13,7 @@
#include <list>
#include <cassert>
+#include <functional>
#include "test_macros.h"
#include "min_allocator.h"
diff --git a/libcxx/test/std/experimental/memory/memory.resource.aliases/header_map_synop.pass.cpp b/libcxx/test/std/experimental/memory/memory.resource.aliases/header_map_synop.pass.cpp
--- a/libcxx/test/std/experimental/memory/memory.resource.aliases/header_map_synop.pass.cpp
+++ b/libcxx/test/std/experimental/memory/memory.resource.aliases/header_map_synop.pass.cpp
@@ -26,6 +26,7 @@
#include <experimental/memory_resource>
#include <type_traits>
#include <cassert>
+#include <functional>
#include "test_macros.h"
diff --git a/libcxx/test/std/experimental/memory/memory.resource.aliases/header_set_synop.pass.cpp b/libcxx/test/std/experimental/memory/memory.resource.aliases/header_set_synop.pass.cpp
--- a/libcxx/test/std/experimental/memory/memory.resource.aliases/header_set_synop.pass.cpp
+++ b/libcxx/test/std/experimental/memory/memory.resource.aliases/header_set_synop.pass.cpp
@@ -26,6 +26,7 @@
#include <experimental/memory_resource>
#include <type_traits>
#include <cassert>
+#include <functional>
#include "test_macros.h"
diff --git a/libcxx/test/std/ranges/range.adaptors/range.drop/dangling.cache.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.drop/dangling.cache.pass.cpp
--- a/libcxx/test/std/ranges/range.adaptors/range.drop/dangling.cache.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.drop/dangling.cache.pass.cpp
@@ -16,6 +16,8 @@
#include <ranges>
+#include <cstring>
+
#include "test_macros.h"
#include "types.h"
diff --git a/libcxx/test/std/re/re.results/re.results.const/copy_assign.pass.cpp b/libcxx/test/std/re/re.results/re.results.const/copy_assign.pass.cpp
--- a/libcxx/test/std/re/re.results/re.results.const/copy_assign.pass.cpp
+++ b/libcxx/test/std/re/re.results/re.results.const/copy_assign.pass.cpp
@@ -14,6 +14,8 @@
#include <regex>
#include <cassert>
+#include <memory>
+#include <type_traits>
#include "test_macros.h"
#include "test_allocator.h"
diff --git a/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/bind_return_type.pass.cpp b/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/bind_return_type.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/bind_return_type.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/bind_return_type.pass.cpp
@@ -22,6 +22,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/invoke_function_object.pass.cpp b/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/invoke_function_object.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/invoke_function_object.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/invoke_function_object.pass.cpp
@@ -19,6 +19,8 @@
#include <functional>
+#include <type_traits>
+
#include "test_macros.h"
struct DummyUnaryFunction
diff --git a/libcxx/test/std/utilities/function.objects/func.identity/identity.pass.cpp b/libcxx/test/std/utilities/function.objects/func.identity/identity.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/func.identity/identity.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.identity/identity.pass.cpp
@@ -15,6 +15,7 @@
#include <cassert>
#include <concepts>
+#include <utility>
#include "MoveOnly.h"
diff --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.badcall/bad_function_call.pass.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.badcall/bad_function_call.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.badcall/bad_function_call.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.badcall/bad_function_call.pass.cpp
@@ -17,6 +17,7 @@
// };
#include <functional>
+#include <exception>
#include <type_traits>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/F_incomplete.pass.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/F_incomplete.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/F_incomplete.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/F_incomplete.pass.cpp
@@ -19,6 +19,7 @@
#include <functional>
#include <cassert>
+#include <type_traits>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_F.verify.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_F.verify.cpp
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_F.verify.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_F.verify.cpp
@@ -18,6 +18,7 @@
#include <functional>
#include <cassert>
+#include <memory>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_function.verify.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_function.verify.cpp
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_function.verify.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/alloc_function.verify.cpp
@@ -18,6 +18,7 @@
#include <functional>
#include <cassert>
+#include <memory>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/copy_assign.pass.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/copy_assign.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/copy_assign.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/copy_assign.pass.cpp
@@ -17,6 +17,7 @@
#include <functional>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "count_new.h"
diff --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/noncopyable_return_type.pass.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/noncopyable_return_type.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/noncopyable_return_type.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/noncopyable_return_type.pass.cpp
@@ -14,6 +14,7 @@
#include <functional>
#include <cassert>
+#include <type_traits>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/range.cmp/equal_to.pass.cpp b/libcxx/test/std/utilities/function.objects/range.cmp/equal_to.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/range.cmp/equal_to.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/range.cmp/equal_to.pass.cpp
@@ -16,6 +16,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "compare_types.h"
diff --git a/libcxx/test/std/utilities/function.objects/range.cmp/greater.pass.cpp b/libcxx/test/std/utilities/function.objects/range.cmp/greater.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/range.cmp/greater.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/range.cmp/greater.pass.cpp
@@ -16,6 +16,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "compare_types.h"
diff --git a/libcxx/test/std/utilities/function.objects/range.cmp/greater_equal.pass.cpp b/libcxx/test/std/utilities/function.objects/range.cmp/greater_equal.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/range.cmp/greater_equal.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/range.cmp/greater_equal.pass.cpp
@@ -16,6 +16,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "compare_types.h"
diff --git a/libcxx/test/std/utilities/function.objects/range.cmp/less.pass.cpp b/libcxx/test/std/utilities/function.objects/range.cmp/less.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/range.cmp/less.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/range.cmp/less.pass.cpp
@@ -16,6 +16,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "compare_types.h"
diff --git a/libcxx/test/std/utilities/function.objects/range.cmp/less_equal.pass.cpp b/libcxx/test/std/utilities/function.objects/range.cmp/less_equal.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/range.cmp/less_equal.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/range.cmp/less_equal.pass.cpp
@@ -16,6 +16,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "compare_types.h"
diff --git a/libcxx/test/std/utilities/function.objects/range.cmp/not_equal_to.pass.cpp b/libcxx/test/std/utilities/function.objects/range.cmp/not_equal_to.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/range.cmp/not_equal_to.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/range.cmp/not_equal_to.pass.cpp
@@ -16,6 +16,7 @@
#include <functional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
#include "compare_types.h"
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
@@ -14,6 +14,7 @@
#include <functional>
#include <cassert>
+#include <type_traits>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/deduct.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/deduct.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/deduct.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/deduct.pass.cpp
@@ -16,6 +16,8 @@
#include <functional>
+#include <type_traits>
+
int main()
{
int i = 0;
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp
@@ -17,6 +17,7 @@
#include <functional>
#include <cassert>
+#include <type_traits>
struct convertible_to_int_ref {
int val = 0;
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor2.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor2.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor2.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor2.pass.cpp
@@ -17,6 +17,7 @@
#include <functional>
#include <cassert>
+#include <type_traits>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/function.objects/unord.hash/enum.pass.cpp b/libcxx/test/std/utilities/function.objects/unord.hash/enum.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/unord.hash/enum.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/unord.hash/enum.pass.cpp
@@ -19,6 +19,7 @@
#include <functional>
#include <cassert>
+#include <cstdint>
#include <type_traits>
#include <limits>
diff --git a/libcxx/test/std/utilities/function.objects/unord.hash/integral.pass.cpp b/libcxx/test/std/utilities/function.objects/unord.hash/integral.pass.cpp
--- a/libcxx/test/std/utilities/function.objects/unord.hash/integral.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/unord.hash/integral.pass.cpp
@@ -21,6 +21,7 @@
#include <cassert>
#include <type_traits>
#include <cstddef>
+#include <cstdint>
#include <limits>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp b/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp
--- a/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp
@@ -15,6 +15,8 @@
#include <optional>
+#include <functional>
+
#include "poisoned_hash_helper.h"
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/explicit_optional_U.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/explicit_optional_U.pass.cpp
--- a/libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/explicit_optional_U.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/explicit_optional_U.pass.cpp
@@ -15,6 +15,7 @@
#include <optional>
#include <type_traits>
#include <cassert>
+#include <utility>
#include "test_macros.h"
diff --git a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp
--- a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp
+++ b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp
@@ -17,6 +17,7 @@
#include <tuple>
#include <cassert>
+#include <memory>
#include "test_macros.h"
#include "MoveOnly.h"
diff --git a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/move.pass.cpp b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/move.pass.cpp
--- a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/move.pass.cpp
+++ b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/move.pass.cpp
@@ -17,6 +17,7 @@
#include <tuple>
#include <utility>
#include <cassert>
+#include <memory>
#include "test_macros.h"
#include "MoveOnly.h"
diff --git a/libcxx/test/std/utilities/utility/utility.intcmp/intcmp.in_range/in_range.pass.cpp b/libcxx/test/std/utilities/utility/utility.intcmp/intcmp.in_range/in_range.pass.cpp
--- a/libcxx/test/std/utilities/utility/utility.intcmp/intcmp.in_range/in_range.pass.cpp
+++ b/libcxx/test/std/utilities/utility/utility.intcmp/intcmp.in_range/in_range.pass.cpp
@@ -19,6 +19,7 @@
#include <numeric>
#include <tuple>
#include <cassert>
+#include <cstdint>
#include "test_macros.h"