Or you could just reproduce the original license, which is all that's required. It's really the stripping of the license out of the file that is the problem, s

Or you could just reproduce the original license, which is all that's required. It's really the stripping of the license out of the file that is the problem, since the original LLVM license specifically states that the license grant is incumbent upon keeping the license text in place. Even though in reality you copied/pasted the text out in to a new file, it's really the equivalent of removing the license text and all of the other code you didn't need.