Capped 43 times for Scotland between 1969 and 1979, he was best known for his role in the victorious Lions tours of New Zealand and South Africa in 1971 and 1974.
He was one of only five players to feature in all eight Test matches on both Tours and his only Test try came against New Zealand in 1971, when he famously charged down an attempted All Blacks clearance to touch down in a 9-3 win.
Undersized at just over 14st (89 kilos) for a prop, McLauchlan earned the nickname "Mighty Mouse" for his ability to burrow under heavier opponents and give his team a set-piece advantage at a time when scrums were much more prevalent in the game.
He later served as a member of the Scottish Rugby Board from 2010 to 2019 and was president of the Scottish Rugby Union between 2010 and 2012.
"He was so tough, almost indestructible," his former Scotland and Lions team-mate Andy Irvine told scottishrugby.org.
"What a fantastic career he had for Scotland and the Lions. It's very, very sad."