What could he have that he would make a raise like this and you beat?
The only hands you are beating are A10, K10, Q10, J10 combinations plus flush draws (but even flush draws have lots of equity against you.) If he is a tilting massive bluffer, its a fine play....but you need lots of evidence to conclude this besides one hand.
However, if he only does this play with sets, flush draws, and two pair (56 being the only likely two pair) then your equity is pretty bad even though you are ahead of some flush draws.
Having a HUD helps.....if this player has low aggression stats than it's a fold.
Having said all that.......his raise size indicates strength. So......lets compare your hand to the following possibilities.
100,000 iterations from free Poker Odds (http://www.pokerranges.com/Poker-Odds-JhJs-on-6c5cTd-board-691.php)-Calculator
at PokerRanges.com (http://www.pokerranges.com): (I found these resources online and have no affiliation with them, just thought it would be helpful)
Hero's hand: J♥ J♠
| Board: 6♣ 5♣ T♦
Range: AT, JT, KT, QT, 55-66, TT, KcAc, QcKc, JcQc, TcJc, 9cTc, 8c9c, 7c8c