diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1bf9288ee9b..c30e4d43620 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2013-01-17  Jan Hubicka  <jh@suse.cz>
+
+	PR tree-optimization/51083
+	* loop-iv.c (iv_number_of_iterations): Consider zero iteration case.
+
 2012-01-17  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/55981
diff --git a/gcc/loop-iv.c b/gcc/loop-iv.c
index 62a3c6f03e5..15f16619863 100644
--- a/gcc/loop-iv.c
+++ b/gcc/loop-iv.c
@@ -2819,7 +2819,8 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
   else
     {
       max = determine_max_iter (loop, desc, old_niter);
-      gcc_assert (max);
+      if (!max)
+	goto zero_iter_simplify;
       if (!desc->infinite
 	  && !desc->assumptions)
 	record_niter_bound (loop, double_int::from_uhwi (max),
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index dc25943f8cd..108f308629b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-01-17  Jan Hubicka  <jh@suse.cz>
+
+	PR tree-optimization/51083
+	* gcc.c-torture/compile/pr51083.c: New testcase.
+
 2012-01-17  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/55981
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr51083.c b/gcc/testsuite/gcc.c-torture/compile/pr51083.c
new file mode 100644
index 00000000000..8ae5199b789
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr51083.c
@@ -0,0 +1,18 @@
+extern int debug_threads;
+extern void sigsuspend (void);
+void my_waitpid (int flags, int wnohang)
+{
+  while (1)
+    {
+      if (flags & 0x80000000)
+        {
+          if (wnohang)
+            break;
+          if (debug_threads)
+            __builtin_puts ("blocking\n");
+          sigsuspend ();
+        }
+      flags ^= 0x80000000;
+    }
+}
+