FYI: I ported X13 and X15 to my fork of pooler's CPU miner. The code is based upon pooler's latest code + AES_NI optimized X11 miner code. The reason for the fork is to add more coins to pooler's miner. Thus I added a kind of plug-in structure (You can add new coins without chaining the core of the cpu miner).

Currently, (n)scrypt, sha256 and X11-X15 are supported. AES_NI is, however, not working at the moment and I don't know why. But even without AES_NI support, the miner produces ~ 1.3 times the hashes per second of the original cpu miner (tested on a Phenom-X4).

https://github.com/oleid/cpuminer

I repeat: AES_NI is broken at the moment. Thus, do not compile using "-march=native". Otherwise the configure script might detect AES_NI and use it, if your machine supports it.