https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
--- Comment #49 from Campbell <rlcamp.pdx at gmail dot com> --- I can confirm that the latest gcc 8 snapshot still fails by default, but it works with 8 cores using Chris's fix above of replacing ln -s with cp. This in my mind pretty conclusively points to it not being a makefile logic error, but rather a filesystem error. However, regardless of whose fault it is, Chris's patch represents an actual viable solution to the problem, and is simple to understand, and does not unduly penalize other platforms. This situation has persisted for far too long and it makes GCC look bad and lose actual users, regardless of whether Apple or GCC caused the problem.