"This medicine will make you feel better."
Translation:Este remédio fará com que você se sinta melhor.
Both "fará que" and "fará com que" can be used here, but the second one just sounds better and you'll hear most native speakers talking like that. It's a weird exception to the rule that a verb that needs a direct object can't have a preposition. I don't know why it happens, but when "fazer" has the meaning of to cause/to induce, that's how people say it.