for some reason libcxx.imp isnt generated

Index: libcxx/include/CMakeLists.txt
--- libcxx/include/CMakeLists.txt.orig
+++ libcxx/include/CMakeLists.txt
@@ -1033,15 +1033,6 @@ foreach(f ${files})
   list(APPEND _all_includes "${dst}")
 endforeach()
 
-# Generate the IWYU mapping. This depends on all header files but it's also considered as an
-# "include" for dependency tracking.
-add_custom_command(OUTPUT "${LIBCXX_GENERATED_INCLUDE_DIR}/libcxx.imp"
-  COMMAND "${Python3_EXECUTABLE}" "${LIBCXX_SOURCE_DIR}/utils/generate_iwyu_mapping.py" "-o" "${LIBCXX_GENERATED_INCLUDE_DIR}/libcxx.imp"
-  DEPENDS ${_all_includes}
-  COMMENT "Generate the mapping file for include-what-you-use"
-)
-list(APPEND _all_includes "${LIBCXX_GENERATED_INCLUDE_DIR}/libcxx.imp")
-
 add_custom_target(generate-cxx-headers ALL DEPENDS ${_all_includes})
 
 add_library(cxx-headers INTERFACE)
@@ -1070,12 +1061,6 @@ if (LIBCXX_INSTALL_HEADERS)
 
   # Install the generated __assertion_handler file to the generic include dir.
   install(FILES "${LIBCXX_GENERATED_INCLUDE_DIR}/__assertion_handler"
-    DESTINATION "${LIBCXX_INSTALL_INCLUDE_DIR}"
-    PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
-    COMPONENT cxx-headers)
-
-  # Install the generated IWYU file to the generic include dir.
-  install(FILES "${LIBCXX_GENERATED_INCLUDE_DIR}/libcxx.imp"
     DESTINATION "${LIBCXX_INSTALL_INCLUDE_DIR}"
     PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
     COMPONENT cxx-headers)
