Reinstall assembler, /usr/bin/as I've lost /usr/bin/as. How does one reinstall it?

There's no as in the /usr/bin of my recovery partition. Reinstalling XCode and command line tools didn't help. I haven't been successful compiling gas from source because I get a linking error. (Is the default in fact gas?)

https://stackoverflow.com/questions/24308125/linking-errors-and-bfd-bfd-gnu-binutils-2-24-assertion-fail

I suspect that the gas program I'm trying to compile might solve the compiling problems I'm having but that does me no good.
Here's a copy of /usr/bin/as from OS X 10.9.4.

With regard to how you'd actually get it back, you might be able to extract it from the install media if you have it or by reinstalling the OS. See How can I get back a system file after deleting it from my Mac?