/usr/lib/x86_64-linux-gnu/libLLVM-6.0.so is in libllvm6.0 1:6.0-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libLLVM-6.0.so.1
/usr/lib/x86_64-linux-gnu/libLLVM-6.0.so.1