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
@@ -1671,7 +1671,6 @@
     module conjunction                               { private header "__type_traits/conjunction.h" }
     module copy_cv                                   { private header "__type_traits/copy_cv.h" }
     module copy_cvref                                { private header "__type_traits/copy_cvref.h" }
-    module datasizeof                                { private header "__type_traits/datasizeof.h" }
     module decay                                     {
       private header "__type_traits/decay.h"
       export add_pointer