is there a script for recursing the compiler?

Do you mean for performing a self-host build, i.e. in which the compiler is
built by (say) gcc, and then is used to build itself? The buildbots do this,
and you can find the logic in the zorg subversion repository at
   http://llvm.org/svn/llvm-project/zorg/trunk/zorg/buildbot/builders
Also, the dragonegg plugin comes with such a script, see
   http://llvm.org/svn/llvm-project/dragonegg/trunk/extras/do_self_strap

Ciao, Duncan.