Proto-Indo-European *gleubʰ- "to cleave" became Proto-Germanic *kleuƀ-, then Old English clēofan "to separate, split", then English cleave.
In Greek, *gleubʰ- became γλύφω "to carve", and this was borrowed into English as glyph. Hieroglyph is from Greek ἱερος "holy" plus glyph.
cleave "to stick fast, adhere" is derived from a wholly unrelated verb: Old English clīfan "to adhere". This verb is now regular, with the past tense/past participle cleaved. Cleave "to separate" kept the strong verb forms clove and cloven, and also the form cleft, which is now differentiated from cloven in some words, like cloven hoof vs cleft palate.