The "Indecent Proposal" star took to Instagram to share cute baby pictures of the actress, her eldest child from her marriage to Bruce Willis, and praised her in a heartwarming post.
"I am a few min late but YOU @rumerwillis my sweet first born came on your due date ready for action and have been in the driver's seat ready for this journey from the day you were born!," Demi wrote alongside a snap of Rumer as a tot in the front seat of a convertible. "Happy Birthday Baby Ru! Before you I didn't really know what love was! You continue to light the pathway of loving and I am honored to be on this ride with you my angel!"
"Thank you for being a beautiful teacher and a magnificent being. I love you beyond measure!" the 56-year-old added.
The "Ghost" star later posted another picture of herself napping with Rumer and added the caption: "Heaven! Happy Birthday and sweet dreams my sweet angel Rumer Glenn @rumerwillis."
The sweet posts come days after Rumer took to social media to reveal that she had been struggling with health issues for several weeks, leaving her "exhausted, overwhelmed and broken down."
"It's my birthday tomorrow and I wanted to start my new year letting go of mindsets, beliefs and old stories that no longer serve me," she stated.