Uh, cmucl required an existing cmucl, SBCL was explicitly forked of that to simplify the bootstrapping by allowing any standard compliant CL compiler as host.

Uh, cmucl required an existing cmucl, SBCL was explicitly forked of that to simplify the bootstrapping by allowing any standard compliant CL compiler as host. On MacOS Clozure CL might be the obvious choice. Well, that's the idea at least, I haven't actually tried it (long time ago, I did compile sbcl with CLISP on Linux/x86-64, which worked fine).