diff --git a/libcxx/include/__algorithm/sort.h b/libcxx/include/__algorithm/sort.h
--- a/libcxx/include/__algorithm/sort.h
+++ b/libcxx/include/__algorithm/sort.h
@@ -15,6 +15,7 @@
 #include <__algorithm/partial_sort.h>
 #include <__algorithm/unwrap_iter.h>
 #include <__config>
+#include <__functional/operations.h>
 #include <__utility/swap.h>
 #include <memory>
 
diff --git a/libcxx/include/__format/format_arg.h b/libcxx/include/__format/format_arg.h
--- a/libcxx/include/__format/format_arg.h
+++ b/libcxx/include/__format/format_arg.h
@@ -16,7 +16,9 @@
 #include <__format/format_error.h>
 #include <__format/format_fwd.h>
 #include <__format/format_parse_context.h>
+#include <__functional/invoke.h>
 #include <__memory/addressof.h>
+#include <__utility/forward.h>
 #include <__utility/unreachable.h>
 #include <__variant/monostate.h>
 #include <string>
diff --git a/libcxx/include/experimental/coroutine b/libcxx/include/experimental/coroutine
--- a/libcxx/include/experimental/coroutine
+++ b/libcxx/include/experimental/coroutine
@@ -47,6 +47,7 @@
 
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__functional/hash.h>
+#include <__functional/operations.h>
 #include <cstddef>
 #include <experimental/__config>
 #include <memory> // for hash<T*>
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
@@ -206,6 +206,7 @@
 #include <__hash_table>
 #include <algorithm>
 #include <ext/__hash>
+#include <functional>
 #include <stdexcept>
 #include <type_traits>
 
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
@@ -197,6 +197,7 @@
 #include <__hash_table>
 #include <algorithm>
 #include <ext/__hash>
+#include <functional>
 
 #if defined(__DEPRECATED) && __DEPRECATED
 #if defined(_LIBCPP_WARNING)
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -684,12 +684,6 @@
 #include <version>
 
 // TODO: remove these headers
-#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>
diff --git a/libcxx/include/map b/libcxx/include/map
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -532,7 +532,9 @@
 #include <__algorithm/lexicographical_compare.h>
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
+#include <__functional/binary_function.h>
 #include <__functional/is_transparent.h>
+#include <__functional/operations.h>
 #include <__iterator/iterator_traits.h>
 #include <__node_handle>
 #include <__tree>
diff --git a/libcxx/include/memory b/libcxx/include/memory
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -872,14 +872,6 @@
 #include <typeinfo>
 #include <version>
 
-// TODO: remove these headers
-#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>
-
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 #   include <__memory/auto_ptr.h>
 #endif
diff --git a/libcxx/include/queue b/libcxx/include/queue
--- a/libcxx/include/queue
+++ b/libcxx/include/queue
@@ -222,6 +222,7 @@
 #include <__algorithm/push_heap.h>
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
+#include <__functional/operations.h>
 #include <__iterator/iterator_traits.h>
 #include <__memory/uses_allocator.h>
 #include <__utility/forward.h>
diff --git a/libcxx/include/set b/libcxx/include/set
--- a/libcxx/include/set
+++ b/libcxx/include/set
@@ -476,6 +476,7 @@
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
 #include <__functional/is_transparent.h>
+#include <__functional/operations.h>
 #include <__iterator/iterator_traits.h>
 #include <__node_handle>
 #include <__tree>
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -524,6 +524,7 @@
 #include <__config>
 #include <__debug>
 #include <__format/enable_insertable.h>
+#include <__functional/unary_function.h>
 #include <__ios/fpos.h>
 #include <__iterator/wrap_iter.h>
 #include <__memory/allocate_at_least.h>
@@ -547,12 +548,6 @@
 #include <version>
 
 // TODO: remove these headers
-#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 <new>
 #include <typeinfo>
 
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -199,6 +199,7 @@
 #include <__algorithm/min.h>
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
+#include <__functional/unary_function.h>
 #include <__fwd/string_view.h>
 #include <__ranges/concepts.h>
 #include <__ranges/data.h>
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -185,12 +185,6 @@
 #include <version>
 
 // TODO: remove these headers
-#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 <exception>
 #include <new>
 #include <typeinfo>
diff --git a/libcxx/include/typeindex b/libcxx/include/typeindex
--- a/libcxx/include/typeindex
+++ b/libcxx/include/typeindex
@@ -52,11 +52,6 @@
 #include <version>
 
 // TODO: remove these headers
-#include <__functional/binary_function.h>
-#include <__functional/invoke.h>
-#include <__functional/operations.h>
-#include <__functional/reference_wrapper.h>
-#include <__functional/weak_result_type.h>
 #include <__memory/allocator_arg_t.h>
 #include <__memory/uses_allocator.h>
 #include <new>
diff --git a/libcxx/include/unordered_map b/libcxx/include/unordered_map
--- a/libcxx/include/unordered_map
+++ b/libcxx/include/unordered_map
@@ -519,6 +519,7 @@
 #include <__config>
 #include <__debug>
 #include <__functional/is_transparent.h>
+#include <__functional/operations.h>
 #include <__hash_table>
 #include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
diff --git a/libcxx/include/unordered_set b/libcxx/include/unordered_set
--- a/libcxx/include/unordered_set
+++ b/libcxx/include/unordered_set
@@ -464,6 +464,7 @@
 #include <__config>
 #include <__debug>
 #include <__functional/is_transparent.h>
+#include <__functional/operations.h>
 #include <__hash_table>
 #include <__memory/addressof.h>
 #include <__node_handle>
diff --git a/libcxx/include/variant b/libcxx/include/variant
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -221,10 +221,6 @@
 #include <version>
 
 // TODO: remove these headers
-#include <__functional/binary_function.h>
-#include <__functional/invoke.h>
-#include <__functional/reference_wrapper.h>
-#include <__functional/weak_result_type.h>
 #include <__memory/allocator_arg_t.h>
 #include <__memory/uses_allocator.h>
 #include <typeinfo>
diff --git a/libcxx/include/vector b/libcxx/include/vector
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -285,6 +285,7 @@
 #include <__debug>
 #include <__format/enable_insertable.h>
 #include <__functional/hash.h>
+#include <__functional/unary_function.h>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/wrap_iter.h>
 #include <__memory/allocate_at_least.h>
@@ -305,12 +306,6 @@
 #include <version>
 
 // TODO: remove these headers
-#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 <typeinfo>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/test/libcxx/algorithms/debug_less.pass.cpp b/libcxx/test/libcxx/algorithms/debug_less.pass.cpp
--- a/libcxx/test/libcxx/algorithms/debug_less.pass.cpp
+++ b/libcxx/test/libcxx/algorithms/debug_less.pass.cpp
@@ -17,8 +17,9 @@
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DEBUG=1
 
 #include <algorithm>
-#include <iterator>
 #include <cassert>
+#include <functional>
+#include <iterator>
 
 #include "test_macros.h"
 #include "check_assertion.h"
diff --git a/libcxx/test/libcxx/algorithms/sort_stability.pass.cpp b/libcxx/test/libcxx/algorithms/sort_stability.pass.cpp
--- a/libcxx/test/libcxx/algorithms/sort_stability.pass.cpp
+++ b/libcxx/test/libcxx/algorithms/sort_stability.pass.cpp
@@ -16,6 +16,7 @@
 #include <algorithm>
 #include <array>
 #include <cassert>
+#include <functional>
 #include <iterator>
 #include <vector>
 
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/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
@@ -13,6 +13,7 @@
 
 #include <chrono>
 #include <concepts>
+#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
@@ -13,6 +13,7 @@
 
 #include <chrono>
 #include <concepts>
+#include <functional>
 #include <memory>
 #include <random>
 #include <type_traits>
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
@@ -11,9 +11,10 @@
 // template <class BinaryPredicate> void unique(BinaryPredicate binary_pred);      // C++17 and before
 // template <class BinaryPredicate> size_type unique(BinaryPredicate binary_pred); // C++20 and after
 
+#include <cassert>
 #include <forward_list>
+#include <functional>
 #include <iterator>
-#include <cassert>
 
 #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/language.support/support.coroutines/coroutine.handle/coroutine.handle.hash/hash.pass.cpp b/libcxx/test/std/experimental/language.support/support.coroutines/coroutine.handle/coroutine.handle.hash/hash.pass.cpp
--- a/libcxx/test/std/experimental/language.support/support.coroutines/coroutine.handle/coroutine.handle.hash/hash.pass.cpp
+++ b/libcxx/test/std/experimental/language.support/support.coroutines/coroutine.handle/coroutine.handle.hash/hash.pass.cpp
@@ -23,6 +23,7 @@
 #include <utility>
 #include <cstdint>
 #include <cassert>
+#include <functional>
 
 #include "test_macros.h"
 
diff --git a/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/types.pass.cpp b/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/types.pass.cpp
--- a/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/types.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/move.iterators/move.iterator/types.pass.cpp
@@ -22,6 +22,7 @@
 //   typedef value_type&&          reference;
 // };
 
+#include <functional>
 #include <iterator>
 #include <type_traits>
 
diff --git a/libcxx/test/std/numerics/numeric.ops/reduce/reduce_init_op.pass.cpp b/libcxx/test/std/numerics/numeric.ops/reduce/reduce_init_op.pass.cpp
--- a/libcxx/test/std/numerics/numeric.ops/reduce/reduce_init_op.pass.cpp
+++ b/libcxx/test/std/numerics/numeric.ops/reduce/reduce_init_op.pass.cpp
@@ -16,6 +16,7 @@
 
 #include <numeric>
 #include <cassert>
+#include <functional>
 
 #include "test_macros.h"
 #include "test_iterators.h"
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.view/sentinel/eq.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.view/sentinel/eq.pass.cpp
--- a/libcxx/test/std/ranges/range.adaptors/range.join.view/sentinel/eq.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.view/sentinel/eq.pass.cpp
@@ -15,6 +15,7 @@
 
 #include <cassert>
 #include <concepts>
+#include <functional>
 #include <ranges>
 
 #include "../types.h"
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/types.h b/libcxx/test/std/ranges/range.adaptors/range.zip/types.h
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/types.h
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/types.h
@@ -9,6 +9,7 @@
 #ifndef TEST_STD_RANGES_RANGE_ADAPTORS_RANGE_ZIP_TYPES_H
 #define TEST_STD_RANGES_RANGE_ADAPTORS_RANGE_ZIP_TYPES_H
 
+#include <functional>
 #include <ranges>
 
 #include "test_macros.h"
diff --git a/libcxx/test/support/deduction_guides_sfinae_checks.h b/libcxx/test/support/deduction_guides_sfinae_checks.h
--- a/libcxx/test/support/deduction_guides_sfinae_checks.h
+++ b/libcxx/test/support/deduction_guides_sfinae_checks.h
@@ -9,6 +9,7 @@
 #ifndef TEST_SUPPORT_DEDUCTION_GUIDES_SFINAE_CHECKS_H
 #define TEST_SUPPORT_DEDUCTION_GUIDES_SFINAE_CHECKS_H
 
+#include <functional>
 #include <initializer_list>
 #include <memory>
 #include <type_traits>