I am the main author of the (only) LLVM plug-in for Eclipse CDT. It is still in development so might not be suitable for production environment yet. However feel free to test it to find out if it is suitable for your needs.
https://github.com/TuononenP/llvm4eclipsecdt
UPDATE
The latest version is available via official Eclipse update site: http://download.eclipse.org/releases/mars
It is under Programming Languages and is named “C/C++ LLVM-Family Compiler Build Support”.