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/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/equal_to.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/equal_to.h>
 #include <__hash_table>
 #include <__utility/pair.h>
-#include <functional>
 #include <ext/__hash>
 
 #if defined(__DEPRECATED) && __DEPRECATED
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/less.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/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 +146,10 @@
 
 #include <__config>
 #include <__debug>
+#include <__functional/multiplies.h>
+#include <__functional/plus.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
@@ -149,13 +149,15 @@
 #include <__availability>
 #include <__config>
 #include <__debug>
+#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/less.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/less.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/thread b/libcxx/include/thread
--- a/libcxx/include/thread
+++ b/libcxx/include/thread
@@ -91,7 +91,6 @@
 #include <__utility/move.h>
 #include <chrono>
 #include <cstddef>
-#include <functional>
 #include <iosfwd>
 #include <memory>
 #include <system_error>
diff --git a/libcxx/include/unordered_map b/libcxx/include/unordered_map
--- a/libcxx/include/unordered_map
+++ b/libcxx/include/unordered_map
@@ -434,6 +434,7 @@
 #include <__config>
 #include <__debug>
 #include <__functional/__is_transparent.h>
+#include <__functional/equal_to.h>
 #include <__hash_table>
 #include <__node_handle>
 #include <__utility/forward.h>
@@ -441,7 +442,6 @@
 #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
@@ -389,6 +389,7 @@
 #include <__config>
 #include <__debug>
 #include <__functional/__is_transparent.h>
+#include <__functional/equal_to.h>
 #include <__hash_table>
 #include <__node_handle>
 #include <__utility/declval.h>
@@ -396,7 +397,6 @@
 #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 +340,27 @@
 */
 
 #include <__config>
+#include <__functional/bit_and.h>
+#include <__functional/bit_or.h>
+#include <__functional/bit_xor.h>
+#include <__functional/equal_to.h>
+#include <__functional/divides.h>
+#include <__functional/greater.h>
+#include <__functional/greater_equal.h>
+#include <__functional/less.h>
+#include <__functional/less_equal.h>
+#include <__functional/logical_and.h>
+#include <__functional/logical_not.h>
+#include <__functional/logical_or.h>
+#include <__functional/minus.h>
+#include <__functional/modulus.h>
+#include <__functional/multiplies.h>
+#include <__functional/negate.h>
+#include <__functional/not_equal_to.h>
+#include <__functional/plus.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 +201,12 @@
 
 #include <__availability>
 #include <__config>
+#include <__functional/equal_to.h>
+#include <__functional/greater.h>
+#include <__functional/greater_equal.h>
+#include <__functional/less.h>
+#include <__functional/less_equal.h>
+#include <__functional/not_equal_to.h>
 #include <__utility/declval.h>
 #include <__utility/forward.h>
 #include <__utility/in_place.h>
@@ -210,7 +216,6 @@
 #include <array>
 #include <compare>
 #include <exception>
-#include <functional>
 #include <initializer_list>
 #include <limits>
 #include <new>
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/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.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/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/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"