Tim Cook answered
The phrase 'God bless you' translates into Hawaiian as 'Ke Akua Hoomaikai Oe'. If you were saying this as a farewell, you could also say 'Ke Akua pu a hui hou' which means 'God bless you and goodbye.'
Other Spiritual Phrases in Hawaiian
God is love - Aloha ke akua (Aloha is 'love' but can also be used as a general greeting or farewell in Hawaii).
Family god or spirit - 'Aumakua
Thanks be to God for this day - Mahalo E Ke Akua No Keia La
May blessings be ever with you - E pili mau na pomaika`i ia `oe
Happy Christmas - Mele kalikimaka
God's house of grace - Ke aloha o ke Hale Akua
The survival of the native Hawaiian language is a constant concern in Hawaii, and can provoke lively debate, as we see in this PBS discussion show: