You could do something like this:

#!/usr/bin/perl -w
use strict;

my @fh;
# open all files
for my $i (0..$#ARGV) {
    open $fh[$i], "<", $ARGV[$i] or die $!;
}

while (1) {
    my @lines;
    # read one line from each file
    push @lines, scalar readline $fh[$_] for 0..$#ARGV;
    
    last unless defined $lines[0];
    chomp @lines;
    print join(",", @lines), "\n";
}
[download]

$ ./950649.pl infile1 infile2 infile3 ... > outfile
[download]

(Note that you have to use readline with "complex" file handle expressions like $fh[$i], as <$fh[$i]> wouldn't work here.)