CLEVELAND — J.R. Smith made seven 3-pointers and the Cleveland Cavaliers drained an NBA-record 25 3s in a 123-98 runaway win over the Atlanta Hawks on Wednesday night in Game 2 of their second-round series.

The Cavs made 18 3-pointers in the first half and added seven more after halftime to embarrass the Hawks, who have lost 10 straight postseason games to Cleveland.

Cleveland’s 25 3s are the most in any game – regular or postseason.

LeBron James made four 3s and scored 27 points for the defending Eastern Conference champions, who put on a display of outside marksmanship unlike any in league history. The Cavs hardly missed.

Even their furry mascot, Moondog, got in on the act by making an over-the-head, backward fling from half court on his first try in the final minutes.

Reserve Dahntay Jones made the record-breaking 24th 3 with 2:24 left, bettering the mark of 23 previously held by Orlando (2009) and Houston (2013). Mo Williams added another 3 for good measure.

Cleveland finished 25 of 45 behind the arc and had 10 players make at least one 3.

Smith made six 3-pointers in the first half – the Cavs knocked down seven straight during one dizzying stretch – as Cleveland built a 38-point lead over the stunned Hawks, who will head home for Friday’s Game 3 down 2-0 in the series and utterly demoralized.

There was little Atlanta defenders could do against the Cavs, who stood behind the line, took aim and dropped shot after shot after shot.

After making Cleveland’s 16th 3-pointer in the first half, the easygoing Smith skipped back on defense like a little kid on a schoolyard playground as Cleveland’s towel-waving fans danced with delight and smelled blood.

By halftime, the Cavs were up by 36 and within three 3-pointers of the postseason record of 21 set by Golden State on April 24.

At that point even the Hawks were done. The team posted on its official Twitter account, “If you take away their 3s, we’re right in this.”

Cleveland went past Golden State’s record when Irving nailed a 3-pointer with 5:06 left in the third quarter. But that wasn’t even enough to satisfy the ravenous sellout crowd which was still chanting “Let’s Go Cavs!” with Cleveland leading by 40 points.

Paul Millsap scored 16 points and Jeff Teague added 14 for the Hawks.

Here’s the kind of night it was for Atlanta: Millsap knocked down a long 3-pointer to end the first quarter, but replays showed it came after the horn and was disallowed.

Not that it would have mattered much.

Cleveland’s crowd sang the national anthem, and the moment it ended, James stepped out of the orderly line with his teammates, ripped open his warmup jacket and screamed “Let’s Go!”

And off the Cavs went.

James passed Tim Duncan for fifth place on the career postseason scoring, and when he did there was no hint the Cavs would shoot their way into the record books as well.