Olor (Spanish for “smell”) comes from the similar Latin olere “to give off a smell”. Odor and Redolent (which is just a bad smell, after all!) come from the same root.
The curious part is the o-l to o-d transition. This is merely a vestige of the influence of the long-dead Sabine dialects of late Latin. Yes, the same Sabines who were raped. They did transition their l-s to d-s.