Dealing with trolls

its late game were about to team fight and our braum takes off chasing an udyr into the jngl alone while the rest of our team got collapsed on and udyr gets back in 1 second and we get 4v5 stomped. He did this the whole game and I repeatedly asked him not to chase all game, hes basically inting at this point and wont listen. What am I to do besides lose the lp and move on. I tell him he lost us the game and he gives me a smiley face in chat and takes off into the sunset. another W for trolls.