I used the following command to determine which source files were
unneeded:
| for i in `find lib/clang -name '*.o'`
| do
| MATCHES="`(nm -g --defined-only $i; nm -g --defined-only \
| usr.bin/clang/clang/clang) | sed -e 's/.* //' | \
| sort | uniq -d | wc -l`"
| [ $MATCHES -eq 0 ] && echo "$i: unneeded"
| done
This should slightly improve the build times.