This is some solution I came with during a ranked game when, even if clearly winning, the ADC decided to go trolling (not sure why, probably the support farming along with the ADC). So he (or she?) went in jungle and just killing creeps there, so our jungler couldn't farm that much. Also no help...But OK, as long as there was no feed from our ADC, we could continue to put pressure on map and getting closer to enemy nexus. At some point this negative dude started also to tell the enemy team what we were trying to do. Like we go for drake, we go to push top, we plan to take baron, etc. Which was even worse because we were not a 4 premades team to communicate via skype or other chat app. So basically we fought 4 vs 6, still winning that game, but was a harsh one.
The idea would be to have a system of banning such team mates with a very destructive attitude. Better fight 4 vs 5 instead of 4 vs 6. And it's doable because the ranked solo/due doesn't allow teams of 4 premades which can simply ban the 5th element in their game team. Or at least to vote for muting that bad team mate, so he/she cannot share crucial infos to enemy team.