asymptotic analysis

I was wondering: Does knowing that one function is little oh of
another tell you anything about possible C and k values for the big-oh
relationship?

For instance, I can prove that (log x)^5 is o(x) by taking the limit of
the first over the second and using L'Hopital's rule. But this doesn't
tell me anything about C and k witnesses, as far as I can determine...

.