[Rd] parallel build for package? (equivalent of make -j8)

[Whit Armstrong]

I have a package that takes about 20 minutes to compile which tends to
prolong the compile/test/compile cycle.

Does anyone know how to get R CMD check or R CMD INSTALL to use parallel make?

I looked at R CMD INSTALL --help, but I don't see anything obvious
arguments to do this.

Thanks,
Whit