Lisa Marie Presley is honoring her son Benjamin Keough on what would have been his 28th birthday.

Keough died by suicide at the age of 27 on July 12. He was known by many for his resemblance to his grandfather, legendary musician Elvis Presley.

In an Instagram post Wednesday, Lisa Marie Presley described the pain of losing her son.

“My beautiful beautiful angel,” she wrote. “I worshipped the ground you walked on, on this earth and now in Heaven. My heart and soul went with you. The depth of the pain is suffocating and bottomless without you every moment of every day. I will never be the same.”

She continued: “Please wait for me my love, and hold my hand while I stay to continue to protect and raise your little sisters and to be here for Riley. I know you would want that. Happy Birthday my sweet sweet Boy. You were much too good for this world.”

Keough was the son of Lisa Marie Presley and her ex-husband, singer-songwriter Danny Keough. The former couple also share daughter Riley Keough, 31. Lisa Marie Presley also shares twin daughters, Harper and Finley, 12, with guitarist Michael Lockwood, whom she was married to from 2006 to 2016.

Riley Keough also posted about her brother Wednesday, sharing an Instagram album of the siblings through the years.

“Happy Birthday beautiful angel,” she wrote.

Musician Trev Lukather also posted a tribute on Instagram, writing that he misses Keough every day.

“Losing Ben was by far the biggest loss I’ve ever experienced,” he wrote. “It just proves how fragile life is and the appreciation you should have for all of your dear, real, and close friends.”

Lukather also encouraged people to “return the text, call or just reach out.”

“You never know what even the closest to you are going through,” he continued. “We’ll hang again one day. Until then, just keep looking out for us as you do.”

According to an Oct. 1 post from the official Facebook page of Elvis Presley’s Graceland estate, Keough was laid to rest alongside his famous grandfather in the property’s Meditation Garden.

Graceland, located in Memphis, Tennessee, is also the resting place of Keough’s great-grandmother Gladys Presley, great-grandfather Vernon Presley and great-great-grandmother Minnie Mae Presley.

Lisa Marie Presley’s manager, Roger Widynowski, confirmed her son’s death in a statement to USA TODAY in July: “She is completely heartbroken, inconsolable and beyond devastated but trying to stay strong for her (twins) and her oldest daughter Riley. She adored that boy. He was the love of her life.”

Elvis Presley’s grandson Benjamin Keough buried in Graceland alongside King of Rock and Roll

Lisa Marie Presley had a special bond with Keough. She revealed on Twitter in 2012 that on Mother’s Day three years prior, the two got matching Celtic eternity knot tattoos. In 2012, she featured Keough and his siblings in a music video remaking Presley’s 1954 hit “I Love You Because.”

Lisa Marie Presley revealed to CMT in October 2012 that backstage at Nashville’s Grand Ole Opry, people were struck over Keough’s resemblance to Presley. “He was at the Opry and was the quiet storm behind the stage!” she said. “Everybody turned around and looked when he was over there. Everybody was grabbing him for a photo because it is just uncanny. Sometimes I am overwhelmed when I look at him.”

Lisa Marie Presley ‘heartbroken’ over death of son Benjamin Keough, Elvis Presley’s grandson, at 27

If you or someone you know may be struggling with self-harm or suicidal thoughts, you can call the U.S. National Suicide Prevention Lifeline at 800-273-TALK (8255) any time day or night, or chat online.

Crisis Text Line also provides free, 24/7, confidential support via text message to people in crisis when they dial 741741.

'I will never be the same': Elvis Presley's grandson Benjamin Keough mourned on birthday