define i32 @test1(i32 %x, i32 %y) nounwind uwtable readnone ssp {
entry:
  %and = and i32 %y, %x
  %cmp = icmp eq i32 %and, 0
  br i1 %cmp, label %if.then, label %if.end

if.then:                                          ; preds = %entry
  %neg = xor i32 %y, -1
  %and4 = and i32 %neg, %x
  br label %if.end

if.end:                                           ; preds = %if.then, %entry
  %x.addr.0 = phi i32 [ %and4, %if.then ], [ %x, %entry ]
  ret i32 %x.addr.0
}

define i32 @test2(i32 %x, i32 %y) nounwind uwtable readnone ssp {
entry:
  %and = and i32 %y, %x
  %cmp = icmp eq i32 %and, 0
  %neg = xor i32 %y, -1
  %and4 = and i32 %neg, %x
  br i1 %cmp, label %if.then, label %if.end

if.then:                                          ; preds = %entry
  br label %if.end

if.end:                                           ; preds = %if.then, %entry
  %x.addr.0 = select i1 %cmp, i32 %and4, i32 %x
  ret i32 %x.addr.0
}

Try:
  opt -O2 x.ll -S -o -
and
  opt -O2 x.ll -S -o - | llvm-commit/Debug+Asserts/bin/llc -O2 -o -