Try gold, which was developed by Ian Lance Taylor et al. from Google and released as part of GNU binutils package.
From Wikipedia:
The motivation for writing gold was to make a linker that is faster than the GNU linker, especially for large applications coded in C++
I must admit I haven’t tried it myself yet but it’s mentioned on WebKitGTK project webpage.
For more information see an article written by the author of gold: A New ELF Linker.
More importantly, see the work on incremental / parallel / concurrent linking by Sander Mathijs van Veen titled Concurrent Linking with the GNU Gold Linker and the bibliography therein.