diff --git a/clang/lib/Tooling/CMakeLists.txt b/clang/lib/Tooling/CMakeLists.txt
--- a/clang/lib/Tooling/CMakeLists.txt
+++ b/clang/lib/Tooling/CMakeLists.txt
@@ -62,12 +62,6 @@
 
   set(skip_expensive_processing $<OR:$<CONFIG:Debug>,$<NOT:$<BOOL:${CLANG_TOOLING_BUILD_AST_INTROSPECTION}>>>)
 
-
-  set(implicitDirs)
-  foreach(implicitDir ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES})
-    list(APPEND implicitDirs -I ${implicitDir})
-  endforeach()
-
   add_custom_command(
       COMMENT Generate ASTNodeAPI.json
       OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/ASTNodeAPI.json
@@ -81,7 +75,6 @@
         -I ${CMAKE_BINARY_DIR}/tools/clang/include
         -I ${CMAKE_BINARY_DIR}/include
         -I ${CMAKE_SOURCE_DIR}/include
-        ${implicitDirs}
         --json-output-path ${CMAKE_CURRENT_BINARY_DIR}/ASTNodeAPI.json
   )