The music mogul, 55, mentored One Direction on X Factor and went on to sign them to his Syco Records once they'd left the show.
Simon became a father for the first time last year with the birth of son Eric, now 17 months, while reports emerged this week that Louis, 23, is expecting a baby with US-based stylist and friend Briana Jungwirth.
Reps for Louis have not confirmed the news.
According to The Mirror, his boss Simon has been offering advice. A source said: "He told Louis it will obviously be a change. But he knows what an amazing experience being a dad has been for himself."
People magazine in the US reports that Louis phoned Simon three weeks ago to inform him of the baby. An insider said: "Louis was so excited and he wanted to tell Simon himself."
"Simon was absolutely delighted for Louis and told him that becoming a dad was the best thing that had ever happened to him," added the source. "He told him if he ever needed any advice to let him know."
So far, there's been no public comment from Simon, Louis, Briana or any of their family members, although it's been claimed that Louis and Briana's families have met and are happy about the impending arrival.
It's said Louis wants to be fully involved and has attended all of Briana's doctor's appointments so far. He is believed to have enjoyed a few dates with Briana in May and although they're not in a relationship now, they are friends.
Louis split from long-time girlfriend Eleanor Calder in March after four years together. Reports today claim he broke the baby news to her in person in LA and that she is "fine" with it.
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