Please have a look at the wiki!
Current version: LLVM-4.0
You can cite Obfuscator-LLVM using the following Bibtex entry:
@INPROCEEDINGS{ieeespro2015-JunodRWM,
author={Pascal Junod and Julien Rinaldini and Johan Wehrli and Julie Michielin},
booktitle={Proceedings of the {IEEE/ACM} 1st International Workshop on Software Protection, {SPRO'15}, Firenze, Italy, May 19th, 2015},
editor = {Brecht Wyseur},
publisher = {IEEE},
title={Obfuscator-{LLVM} -- Software Protection for the Masses},
year={2015},
pages={3--9},
doi={10.1109/SPRO.2015.10},
}