/usr/lib/x86_64-linux-gnu/libLLVM-4.0.1.so.1 is in llvm-4.0-dev 1:4.0.1-10.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libLLVM-4.0.so.1
/usr/lib/x86_64-linux-gnu/libLLVM-4.0.so.1