/usr/lib/llvm-3.8/include/llvm-c is in llvm-3.8-dev 1:3.8-2ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/llvm-3.8/include/../../../include/llvm-c-3.8/llvm-c
/usr/lib/llvm-3.8/include/../../../include/llvm-c-3.8/llvm-c