As an alternative, why not try compiling your libraries to shared libraries rather than static libraries?
Where I work, one large projects link time was around 6 minutes, this was for only 5 libraries!
My solution was (for a debug version), create .so files alphabetically (libA.so, libB.so etc) so each indivdual link wasn’t too long, and the final link was much shorter, because all the (partial) linking had been done previously. The release version was built in the old fashioned way because there was a perceived ‘danger’ with my new method.
I managed to get a 1 module compile/link cycle down from 6 minutes to 10 seconds using this method.