VIDEO: Watch Billie Lourd Sing 'American Girl' in Honor of Her Mom, Carrie Fisher

Actress Billie Lourd honored her late mother, Carrie Fisher, in an Instagram video posted earlier today. In the clip, Lourd sings Tom Petty's "American Girl" - one of Fisher's favorite songs.

Fisher, herself the daughter of Hollywood royalty Debbie Reynolds and Eddie Fisher, died in December of 2016. Today would have been her 63rd birthday.

She was legendary for playing Princess Leia in the original "Star Wars" trilogy, reprising her role in 2015's "The Force Awakens" and 2017's "The Last Jedi." Fisher was also a fantastic writer and sought-after script doctor; films and one-woman shows were made out of several of her novels and memoirs. What's more, she was a mental health advocate who was loud and open about her bipolar disorder and the ways it impacted her life and career.

Lourd starred in coming-of-age comedy "Booksmart" last year. She's also known for roles on "Scream Queens" and in the latest "Star Wars" trilogy.

She wrote:

American Girl (Tom Petty) - Billie Lourd

Happy birthday Momby. Today would have been my Momby's 63rd birthday. Not that I'm some kind of grief expert by any means, but on milestones (or whatever you want to call them) like this, I like to celebrate her by doing things that she loved to do. So here's a little video of me singing one of her favorite songs (American girl by Tom petty) in one of her favorite places (her bathtub of course). I'll probably have a pint of vanilla haggen daaz and a Coca Cola for dinner.

Watch the moving tribute below!