/usr/lib/x86_64-linux-gnu/libLLVM-3.9.so is in libllvm3.9 1:3.9.1-19ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libLLVM-3.9.so.1
/usr/lib/x86_64-linux-gnu/libLLVM-3.9.so.1