Lo in the orient when the gracious light
Lifts up his burning head, each under eye
Doth homage to his new-appearing sight,
Serving with looks his sacred majesty;
And having climbed the steep-up heavenly hill,
Resembling strong youth in his middle age,
Yet mortal looks adore his beauty still,
Attending on his golden pilgrimage:
In Greek mythology  Phoebus Apollo  drives a chariot up hill — that is, across the sky — to meet the sun god, Helios. 
 
 The compound adjective “steep-up” to describe the hill is concise and inventive.
Sonnet 7