diff --git a/libcxx/include/__filesystem/path.h b/libcxx/include/__filesystem/path.h
--- a/libcxx/include/__filesystem/path.h
+++ b/libcxx/include/__filesystem/path.h
@@ -14,6 +14,7 @@
 #include <__algorithm/replace_copy.h>
 #include <__availability>
 #include <__config>
+#include <__functional/hash.h>
 #include <__functional/unary_function.h>
 #include <__fwd/hash.h>
 #include <__iterator/back_insert_iterator.h>
diff --git a/libcxx/include/__memory/concepts.h b/libcxx/include/__memory/concepts.h
--- a/libcxx/include/__memory/concepts.h
+++ b/libcxx/include/__memory/concepts.h
@@ -19,6 +19,7 @@
 #include <__ranges/concepts.h>
 #include <__type_traits/is_reference.h>
 #include <__type_traits/remove_cvref.h>
+#include <__type_traits/remove_reference.h> // TODO(modules): This should not be required
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
diff --git a/libcxx/include/__ranges/all.h b/libcxx/include/__ranges/all.h
--- a/libcxx/include/__ranges/all.h
+++ b/libcxx/include/__ranges/all.h
@@ -11,6 +11,8 @@
 #define _LIBCPP___RANGES_ALL_H
 
 #include <__config>
+#include <__functional/compose.h>         // TODO(modules): Those should not be required
+#include <__functional/perfect_forward.h> //
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__ranges/access.h>
diff --git a/libcxx/include/__ranges/transform_view.h b/libcxx/include/__ranges/transform_view.h
--- a/libcxx/include/__ranges/transform_view.h
+++ b/libcxx/include/__ranges/transform_view.h
@@ -20,6 +20,7 @@
 #include <__config>
 #include <__functional/bind_back.h>
 #include <__functional/invoke.h>
+#include <__functional/perfect_forward.h>
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
diff --git a/libcxx/include/__system_error/error_condition.h b/libcxx/include/__system_error/error_condition.h
--- a/libcxx/include/__system_error/error_condition.h
+++ b/libcxx/include/__system_error/error_condition.h
@@ -12,6 +12,7 @@
 
 #include <__compare/ordering.h>
 #include <__config>
+#include <__functional/hash.h>
 #include <__functional/unary_function.h>
 #include <__system_error/errc.h>
 #include <__system_error/error_category.h>
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -117,8 +117,6 @@
   }
   module tgmath_h {
     header "tgmath.h"
-    export ccomplex
-    export cmath
     export *
   }
 
@@ -226,7 +224,6 @@
     module cwchar {
       @requires_LIBCXX_ENABLE_WIDE_CHARACTERS@
       header "cwchar"
-      export depr.stdio_h
       export *
     }
     module cwctype {
@@ -502,12 +499,11 @@
       }
       module ranges_partial_sort {
         private header "__algorithm/ranges_partial_sort.h"
-        export algorithm.__algorithm.in_out_result
         export functional.__functional.ranges_operations
       }
       module ranges_partial_sort_copy {
         private header "__algorithm/ranges_partial_sort_copy.h"
-        export algorithm.__algorithm.in_out_out_result
+        export algorithm.__algorithm.in_out_result
         export functional.__functional.ranges_operations
       }
       module ranges_partition                { private header "__algorithm/ranges_partition.h" }
@@ -763,7 +759,6 @@
         private header "__chrono/high_resolution_clock.h"
         export steady_clock
         export system_clock
-        export time_point
       }
       module literals               { private header "__chrono/literals.h" }
       module month                  { private header "__chrono/month.h" }
@@ -778,8 +773,14 @@
         private header "__chrono/parser_std_format_spec.h"
       }
       module statically_widen       { private header "__chrono/statically_widen.h" }
-      module steady_clock           { private header "__chrono/steady_clock.h" }
-      module system_clock           { private header "__chrono/system_clock.h" }
+      module steady_clock           {
+        private header "__chrono/steady_clock.h"
+        export time_point
+      }
+      module system_clock           {
+        private header "__chrono/system_clock.h"
+        export time_point
+      }
       module time_point             { private header "__chrono/time_point.h" }
       module weekday                { private header "__chrono/weekday.h" }
       module year                   { private header "__chrono/year.h" }
@@ -939,7 +940,6 @@
         private header "__format/format_context.h"
         export optional
         export locale
-        export __locale
       }
       module format_error                    { private header "__format/format_error.h" }
       module format_functions                {
@@ -1085,7 +1085,7 @@
       module cpp17_iterator_concepts { private header "__iterator/cpp17_iterator_concepts.h" }
       module concepts {
         private header "__iterator/concepts.h"
-        export concepts.equality_comparable
+        export std.concepts.__concepts.equality_comparable
         export type_traits.common_reference
       }
       module counted_iterator      { private header "__iterator/counted_iterator.h" }
@@ -1120,10 +1120,7 @@
       module permutable            { private header "__iterator/permutable.h" }
       module prev                  { private header "__iterator/prev.h" }
       module projected             { private header "__iterator/projected.h" }
-      module readable_traits       {
-        private header "__iterator/readable_traits.h"
-        export __iterator.iterator_traits
-      }
+      module readable_traits       { private header "__iterator/readable_traits.h" }
       module reverse_access        { private header "__iterator/reverse_access.h" }
       module reverse_iterator      { private header "__iterator/reverse_iterator.h" }
       module segmented_iterator    { private header "__iterator/segmented_iterator.h" }
@@ -1168,12 +1165,14 @@
   }
   module mdspan {
     header "mdspan"
-    export array
-    export span
     export *
 
     module __mdspan {
-      module extents                         { private header "__mdspan/extents.h" }
+      module extents                         {
+        private header "__mdspan/extents.h"
+        export array
+        export span
+      }
       module layout_left                     { private header "__mdspan/layout_left.h" }
       module layout_right                    { private header "__mdspan/layout_right.h" }
       module mdspan_fwd                      { private header "__fwd/mdspan.h" }
@@ -1500,7 +1499,6 @@
   }
   module string_view {
     header "string_view"
-    export initializer_list
     export *
     module string_view_fwd { private header "__fwd/string_view.h" }
   }
@@ -1511,7 +1509,6 @@
   }
   module system_error {
     header "system_error"
-    export __errc
     export *
     module __system_error {
       module errc           { private header "__system_error/errc.h" }
@@ -1876,10 +1873,6 @@
       header "experimental/set"
       export *
     }
-    module span {
-      header "span"
-      export *
-    }
     module string {
       header "experimental/string"
       export *
diff --git a/libcxx/test/libcxx/transitive_includes/cxx03.csv b/libcxx/test/libcxx/transitive_includes/cxx03.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx03.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx03.csv
@@ -285,6 +285,7 @@
 filesystem cstddef
 filesystem cstdint
 filesystem cstdlib
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd
diff --git a/libcxx/test/libcxx/transitive_includes/cxx11.csv b/libcxx/test/libcxx/transitive_includes/cxx11.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx11.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx11.csv
@@ -285,6 +285,7 @@
 filesystem cstddef
 filesystem cstdint
 filesystem cstdlib
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd
diff --git a/libcxx/test/libcxx/transitive_includes/cxx14.csv b/libcxx/test/libcxx/transitive_includes/cxx14.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx14.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx14.csv
@@ -287,6 +287,7 @@
 filesystem cstddef
 filesystem cstdint
 filesystem cstdlib
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd
diff --git a/libcxx/test/libcxx/transitive_includes/cxx17.csv b/libcxx/test/libcxx/transitive_includes/cxx17.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx17.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx17.csv
@@ -287,6 +287,7 @@
 filesystem cstddef
 filesystem cstdint
 filesystem cstdlib
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd
diff --git a/libcxx/test/libcxx/transitive_includes/cxx20.csv b/libcxx/test/libcxx/transitive_includes/cxx20.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx20.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx20.csv
@@ -294,6 +294,7 @@
 filesystem cstddef
 filesystem cstdint
 filesystem cstdlib
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd
diff --git a/libcxx/test/libcxx/transitive_includes/cxx23.csv b/libcxx/test/libcxx/transitive_includes/cxx23.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx23.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx23.csv
@@ -191,6 +191,7 @@
 filesystem compare
 filesystem cstddef
 filesystem cstdint
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd
diff --git a/libcxx/test/libcxx/transitive_includes/cxx26.csv b/libcxx/test/libcxx/transitive_includes/cxx26.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx26.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx26.csv
@@ -191,6 +191,7 @@
 filesystem compare
 filesystem cstddef
 filesystem cstdint
+filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem iosfwd