Formal:
* Que o Senhor o abençoe. (This is the most literal translation and is appropriate for formal occasions or addressing someone you don't know well.)
* Que Deus o abençoe. (This uses "Deus" (God) instead of "Senhor" (Lord) and is also formal.)
Informal:
* Que Deus te abençoe. (This is more informal and uses the informal "te" instead of "o".)
* Que o Senhor te abençoe. (Similar to the above, but with "Senhor" instead of "Deus.")
* Deus te abençoe. (This is the most common and informal way to say "God bless you" in Portuguese.)
Specific to the Lord:
* Que o Senhor te/o abençoe. (This emphasizes "Senhor" (Lord) and is more specific than just saying "God bless you.")
You can also say:
* Que o Senhor te ilumine. (May the Lord enlighten you.)
Remember to choose the phrasing that best fits the context of your conversation and your relationship with the person you are addressing.