/usr/lib/x86_64-linux-gnu/libLLVM-3.5.so is in llvm-3.5-dev 1:3.5~svn201651-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libLLVM-3.5.so.1
/usr/lib/x86_64-linux-gnu/libLLVM-3.5.so.1