Are there attributes that affect how the CLR optimizes during a JIT compile?

As the question says, I am curious if any of you know about attributes that affect how the CLR will compile/optimize the bytecode. Is there an attribute that will affect code inlining decisions? Unroll loops?

Are there undocumented attributes on classes generated for anonymous types/delegates?

There's probably attributes to disable optimizations for debug purposes, but somehow I am not so interested in those.