Billie Lourd has paid tribute to her late grandmother Debbie Reynolds on what would have been her 87th birthday.

The 'Singing In The Rain' star tragically died just days after her daughter - and Billie's mother - Carrie Fisher in December 2016, and to mark what would have been her birthday on Monday (01.04.19), the 26-year-old actress took to Instagram to post a sweet tribute.

Billie posted a picture of herself as a child with her mother and grandmother, and wrote the caption in the signature all-emoji style that 'Star Wars' star Carrie used to use, and which Billie has adopted for many of her posts since her mother's passing.

The caption read: ''Happy birthday abadaba,'' which is a nickname Billie had for her grandmother.

Meanwhile, the 'Booksmart' actress opened up in 2017 about the struggles of coping with the tragic loss of her family members, which she said were ''impossible to deal with''.

She said at the time: ''It's completely surreal. There's no way to really explain it - it's so hard to talk about. If I say I'm doing good, I'm too happy. If I say I'm not doing good, then I'm a mess. So it's really hard to know what to say about it because it's so surreal and impossible to deal with.''

And Billie later admitted her mother's sense of humour had helped her get through the tough time that followed her passing.

She said: ''If life's not funny, then it's just true - and that would be unacceptable. Even when she died, that was what got me through that whole thing. When Debbie died the next day, I could just picture her saying, 'Well, she's upstaging me once again, of course - she had to.' ''