By Mark Lamport-Stokes

KIAWAH ISLAND, South Carolina (Reuters) - Northern Ireland's Rory McIlroy repelled an early onslaught by Britain's Ian Poulter before cruising to his second major title by a record eight shots at the PGA Championship on Sunday.

The 23-year-old McIlroy, who started the final round with a three-shot lead, carded a flawless six-under-par 66 that gave him a 13-under total of 275 in the year's last major.

The mop-haired Northern Irishman sank a 20-foot putt from just off the green to birdie the last in glorious late afternoon sunshine at Kiawah Island Golf Resort, then lifted his putter skywards in celebration.

His victory margin eclipsed the previous best set by golfing great Jack Nicklaus at Oak Hill in 1980 and underlined his burgeoning status as heir apparent to former world number one Tiger Woods.

Britain's David Lynn, competing in his first PGA Championship, birdied two of the last three holes for a 68 to finish alone in second.

Fellow Englishman Poulter, who briefly trimmed McIlroy's lead to one shot after a sizzling five-birdie start, faded after the turn en route to a 69 and a tie for third at four under.

Level with Poulter were his compatriot Justin Rose (66), Swede Carl Pettersson (72) and defending champion Keegan Bradley of the United States (68).

Pettersson, despite being slapped with a two-stroke penalty for grounding his club in a hazard on the first hole, responded well with three birdies in five holes before coming unstuck like so many others on the more difficult back nine.

Four-times champion Woods, hunting his 14th major crown but his first in over four years, had to settle for a share of 11th place at two under after signing off with a 72.

(Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)