A.T. Robertson Commentary 1 Corinthians 11:26

"For as often as ye eat this bread, and drink the cup, ye proclaim the Lord`s death till he come." — 1 Corinthians 11:26 (ASV)

Till he come (αχρ ου ελθη). Common idiom (with or without αν) with the aorist subjunctive for future time (Robertson, Grammar, p. 975). In Lu 22:18 we have εως ου ελθη. The Lord's Supper is the great preacher (καταγγελλετε) of the death of Christ till his second coming (Matthew 26:29).