diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -121,6 +121,7 @@
   math.h
   memory
   module.modulemap
+  module.private.modulemap
   mutex
   new
   numbers
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -1,10 +1,3 @@
-// define the module for __config outside of the top level 'std' module
-// since __config may be included from C headers which may create an
-// include cycle.
-module std_config [system] [extern_c] {
-    header "__config"
-}
-
 module std [system] {
   export std_config
   // FIXME: The standard does not require that each of these submodules
@@ -531,8 +524,6 @@
   module __locale { header "__locale" export * }
   module __mutex_base { header "__mutex_base" export * }
   module __split_buffer { header "__split_buffer" export * }
-  module __sso_allocator { header "__sso_allocator" export * }
-  module __std_stream { header "__std_stream" export * }
   module __string { header "__string" export * }
   module __tree { header "__tree" export * }
   module __tuple { header "__tuple" export * }
diff --git a/libcxx/include/module.private.modulemap b/libcxx/include/module.private.modulemap
new file mode 100644
--- /dev/null
+++ b/libcxx/include/module.private.modulemap
@@ -0,0 +1,7 @@
+module std_Private {
+
+  module __sso_allocator { header "__sso_allocator" export * }
+  module __std_stream { header "__std_stream" export * }
+
+  module __support { umbrella "support" export * }
+}