Illegal aliens should not be illegal any more.
We live in a capitalist global system. I would like to see that changed eventually, but even under the most capitalistic assumptions the right to free labor needs to be fairly sacrosanct.
No right is absolute, of course. But whenever the rights of workers to seek out labor is limited, we all suffer. Workers suffer the most, but even producers are not able to find the best human capital for the job. The whole logic that Ricardo offered, that England could focus on textiles and Portugal on wine to both nation's advantage, is based on the ability of English people good at making wine to be able to go to Portugal. If they can't, they are employed at textiles which they are not good at. And much of the classical economics on which we've based our social systems assumed that people always could leave to a frontier. There is no frontier anymore.
There should be an easy mechanism for citizenship or for green cards, which should of course carry with it all the attendant benefits.