diff --git a/gcc/testsuite/gcc.dg/vect/pr81196-2.c b/gcc/testsuite/gcc.dg/vect/pr81196-2.c
new file mode 100644
index 00000000000..8d5ce6bad53
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr81196-2.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+void b (int *p)
+{
+  p = (int *)__builtin_assume_aligned(p, __BIGGEST_ALIGNMENT__);
+  int *q = p + 255;
+  for(; p < q; ++p, --q)
+    {
+      int t = *p;
+      *p = *q;
+      *q = t;
+    }
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc
index 04c209561d8..d33095b8e03 100644
--- a/gcc/tree-ssa-loop-niter.cc
+++ b/gcc/tree-ssa-loop-niter.cc
@@ -1915,14 +1915,23 @@ number_of_iterations_cond (class loop *loop,
 	}
       /* If the new step of IV0 has changed sign or is of greater
 	 magnitude then we do not know whether IV0 does overflow
-	 and thus the transform is not valid for code other than NE_EXPR  */
+	 and thus the transform is not valid for code other than NE_EXPR.  */
       else if (tree_int_cst_sign_bit (step) != tree_int_cst_sign_bit (iv0->step)
 	       || wi::gtu_p (wi::abs (wi::to_widest (step)),
 			     wi::abs (wi::to_widest (iv0->step))))
 	{
-	  if (code != NE_EXPR)
+	  if (POINTER_TYPE_P (type) && code != NE_EXPR)
+	    /* For relational pointer compares we have further guarantees
+	       that the pointers always point to the same object (or one
+	       after it) and that objects do not cross the zero page.  So
+	       not only is the transform always valid for relational
+	       pointer compares, we also know the resulting IV does not
+	       overflow.  */
+	    ;
+	  else if (code != NE_EXPR)
 	    return false;
-	  iv0->no_overflow = false;
+	  else
+	    iv0->no_overflow = false;
 	}
 
       iv0->step = step;