Last year an initiative started to have the daily latest LLVM code compiled and packaged for various releases of Ubuntu and Debian. These daily packages were tossed into a Debian package archive hosted at LLVM.org.
The packaging has been for Debian Wheezy, Debian Sid, Ubuntu 12.04, Ubuntu 12.10, Ubuntu 13.04, and Ubuntu 13.10. For those users of the service, for the older Debian/Ubuntu Linux releases this package archive has fallen behind and is no longer daily due to lacking GCC 4.8. With LLVM's push towards needing C++11 as the host compiler, GCC 4.8 is needed by the platform for its libstdc++ library.
Sylvestre Ledru of Debian has been maintaining these daily LLVM packages and he explained he might end up dropping support for the older distribution releases over this libstdc++ problem. Here's an unresolved mailing list thread about the situation.
The good news though is that as of yesterday there's daily LLVM/Clang packages being built for the current development state of Ubuntu 14.04. I've been communicating with Sylvestre for getting these daily Ubuntu 14.04 packages going so that an automated benchmarking test farm of the latest LLVM Clang code can be going at Phoronix -- powered by the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org.
Besides LLVM and Clang being in the archive there's also Compiler-RT, Polly, and LLDB. Those wanting to grab the very latest state of LLVM and its sub-projects on your Debian/Ubuntu distribution, drop by LLVM.org/apt/.