/usr/share/doc/llvm-3.9-examples/Makefile.rules is in llvm-3.9-examples 1:3.9.1-19ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/llvm-3.9-examples/../../../lib/llvm-3.9/build/Makefile.rules