I'm not sure why you linked to the darwinports web site, it’s a domain squatting site, not at all linked to the original darwinports project, and I believe one

I'm not sure why you linked to the darwinports web site, it’s a domain squatting site, not at all linked to the original darwinports project, and I believe one of the reasons they changed the name. Even without this, darwinports, not macports, have ever (really) supported binary installs, which means you need a compiler (namely gcc) to get this LLVM package installed.