diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -295,6 +295,11 @@
   module format {
     header "format"
     export *
+
+    // module __format {
+    //   module format_error         { header "__format/format_error.h"         }
+    //   module format_parse_context { header "__format/format_parse_context.h" }
+    // }
   }
   module forward_list {
     header "forward_list"
@@ -346,6 +351,19 @@
   module iterator {
     header "iterator"
     export *
+
+    // module __iterator {
+    //   module advance              { header "__iterator/advance.h"              }
+    //   module concepts             { header "__iterator/concepts.h"             }
+    //   module default_sentinel     { header "__iterator/default_sentinel.h"     }
+    //   module incrementable_traits { header "__iterator/incrementable_traits.h" }
+    //   module iter_move            { header "__iterator/iter_move.h"            }
+    //   module iterator_traits      { header "__iterator/iterator_traits.h"      }
+    //   module next                 { header "__iterator/next.h"                 }
+    //   module prev                 { header "__iterator/prev.h"                 }
+    //   module projected            { header "__iterator/projected.h"            }
+    //   module readable_traits      { header "__iterator/readable_traits.h"      }
+    // }
   }
   module latch {
     requires cplusplus14
@@ -373,6 +391,23 @@
   module memory {
     header "memory"
     export *
+
+    // module __memory {
+    //   module addressof                { header "__memory/addressof.h"                }
+    //   module allocation_guard         { header "__memory/allocation_guard.h"         }
+    //   module allocator_traits         { header "__memory/allocator_traits.h"         }
+    //   module allocator                { header "__memory/allocator.h"                }
+    //   module auto_ptr                 { header "__memory/auto_ptr.h"                 }
+    //   module compressed_pair          { header "__memory/compressed_pair.h"          }
+    //   module construct_at             { header "__memory/construct_at.h"             }
+    //   module pointer_safety           { header "__memory/pointer_safety.h"           }
+    //   module pointer_traits           { header "__memory/pointer_traits.h"           }
+    //   module raw_storage_iterator     { header "__memory/raw_storage_iterator.h"     }
+    //   module shared_ptr               { header "__memory/shared_ptr.h"               }
+    //   module temporary_buffer         { header "__memory/temporary_buffer.h"         }
+    //   module uninitialized_algorithms { header "__memory/uninitialized_algorithms.h" }
+    //   module unique_ptr               { header "__memory/unique_ptr.h"               }
+    // }
   }
   module mutex {
     header "mutex"
@@ -415,6 +450,17 @@
     export initializer_list
     export iterator
     export *
+
+    // module __ranges {
+    //   module access                 { header "__ranges/access.h"                 }
+    //   module concepts               { header "__ranges/concepts.h"               }
+    //   module data                   { header "__ranges/data.h"                   }
+    //   module empty                  { header "__ranges/empty.h"                  }
+    //   module enable_borrowed_range  { header "__ranges/enable_borrowed_range.h"  }
+    //   module enable_view            { header "__ranges/enable_view.h"            }
+    //   module size                   { header "__ranges/size.h"                   }
+    //   module view_interface         { header "__ranges/view_interface.h"         }
+    // }
   }
   module ratio {
     header "ratio"
@@ -512,6 +558,12 @@
     header "utility"
     export initializer_list
     export *
+
+    // module __utility {
+    //   module to_underlying {
+    //     header "__utility/to_underlying.h"
+    //   }
+    // }
   }
   module valarray {
     header "valarray"
@@ -532,16 +584,22 @@
     export *
   }
 
+  // __config not modularised due to a bug in Clang
+  // __functional(_03)?_base not modularised since it's designed for textual inclusion
+  // libcpp_version not modularised since it's just a version number
   // FIXME: These should be private.
+  // module __availability      { header "__availability"      export * }
   module __bit_reference { header "__bit_reference" export * }
   module __bits { header "__bits" export * }
   module __debug { header "__debug" export * }
   module __errc { header "__errc" export * }
+  // module __function_like     { header "__function_like.h"   export * }
   module __functional_base { header "__functional_base" export * }
-  module __hash_table { header "__hash_table" export * }
+  // module __hash_table  { header "__hash_table" export * }
   module __locale { header "__locale" export * }
   module __mutex_base { header "__mutex_base" export * }
   module __node_handle { header "__node_handle" export * }
+  // module __nullptr           { header "__nullptr"           export * }
   module __split_buffer { header "__split_buffer" export * }
   module __std_stream { header "__std_stream" export * }
   module __string { header "__string" export * }