What is the value of a McGill LLB degree in the US and internationally?

I cannot speak for the US. I know that McGill has a fairly good reputation internationally. It would certainly be a good addition to a civil law lawyer's cv to have attended the courses at a top English speaking Canadian University.

I live in Boston and know several McGill graduates working here, as well in other American cities, although mainly in large firms doing international work. In recent years there has been increasingly aggressive recruitment at McGill by top US firms. In my experience, students from McGill do very well internationally, although all the graduates I know have the LLB/BCL dual degrees.