This is a follow up on https://reviews.llvm.org/D101528
LGTM with one additional suggestion.
May be add something like this below this line:
if(LLVM_LIBC_ENABLE_LINTING AND (NOT LLVM_LIBC_FULL_BUILD)) message(FATAL_ERROR "Cannot enable linting when full libc build is not enabled.") endif()
Linting, as implemented currently, is meaningless when not using LLVM libc headers.