When you type "perl Makefile.PL" the Makefile is generated by MakeMaker.
MakeMaker is a very cross-platform, Makefile generation tool specific to installing Perl modules. It works on every operating system that Perl does, and that means a LOT of operating systems. All Unixen, all versions of Windows and yes, VMS. MakeMaker works with many different flavors and versions of make including GNU make, nmake, dmake, mms and mmk.
If you're looking for some hard core cross platform code, look no further.
MakeMaker is always looking for more testers and contributors using non-mainstream operating systems and makes.
MakeMaker hopes to be retired someday, perhaps by Module::Build.