This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development is uncertain. The character combines 麥 (wheat) and 來 (come), but the original semantic or phonetic role is unclear.
The left side 麥 suggests wheat, and the right side 來 suggests coming. Picture wheat coming in, but the overall meaning is unclear.
For ライ, imagine a line of wheat coming in: line -> ライ, though the kanji's meaning is uncertain.