I would also like to report 4 of 788 tests failed with Clang using: Mac OSX 10.7.3 Lion clang-3.1 (318) automake-1.11.3 autoconf-2.68 gawk-4.0.0 Attached are my test results. I think I noticed some were minor things, where the test code met unexpected arguments in my CFLAGS. Those are probably fixed in HEAD already, but in case they are not, here is some background info: Clang has some strange ways of sending flags to the linker or preprocessor. Most people are familiar with the -Wl,-shared sort of notation for gcc and the linker, but with Clang my CFLAGS when using Homebrew contain items like these -w -pipe -march=native -Xclang -target-feature -Xclang -aes Ok thanks for your help on this and my previous bug report.