I think the OP is talking about shirt stink, not pit stink. Heck, for pit stink just take some deodorant. K.I.S.S. You can cut a chunk off of a stick and put it into one of those mini-balm containers, and microwave it so that it melts into the container. Rub it on with your finger.
For shirt stink, eh, your kinda screwed unless you wash it. Even merino will stink eventually, though it takes longer than synthetics.