What was Miley Cyrus's original first name?

Her birth name was Destiny Hope Cyrus, but in March 2008, when she was 15, she filed papers in the Los Angeles Superior Court to have her name legally changed to Miley Ray Cyrus. Since she always smiled, her parents nicknamed her "Smiley" which was later shortened to "Miley". She changed her middle name to Ray not because her father's middle name is Ray (her father is Billy Ray Cyrus) but to honour her beloved late grandfather (and Billy Ray's father), the Democratic politician Ronald Ray Cyrus, who died February 28th, 2006.
Miley Cyrus is her current legal name, hence it is her "real name" at least in some context. However, it was not the name she was born with.

Miley Cyrus' birth name was Destiny Hope Cyrus, but when she was 15 she changed her name to Miley. Her friends and family had always called her smiley because she smiled a lot and that changed to Miley. She later legally changed her name.