Mafi again looked dangerous with ball in hand, and replacement Peter Stringer added some pace to the visitors' late forays.
But there was no sign of Leinster wilting and a late surge from O'Driscoll and D'Arcy showed the potency they possess.
Having guided Leinster to their fourth victory on the trot over Munster - something they had not achieved before in the professional era - Cheika could be set for a title-winning send-off before he heads to Stade Francais next season.
Speaking after the game, a clearly satisfied Heaslip said: "It was another hard-fought battle and we're delighted to get the win and we're in contention for a bit of silverware, so we're happy.
"For the past couple of seasons we have worked very hard on our defence with Kurt (McQuilkin) and we again showed that today. Not many teams come through us, but credit to Munster because they came at us right until the end.
"They're a top quality side and we're lucky that it's us who have come out on top. The lads really dug deep and we're looking forward to facing the Ospreys in what should be a great game. They're a fantastic side right across the park."
|Leinster Rugby Score Card|
|Munster Rugby Score Card|