diff --git a/gcc/regcprop.cc b/gcc/regcprop.cc
index 1fdc367..5555c4a 100644
--- a/gcc/regcprop.cc
+++ b/gcc/regcprop.cc
@@ -1384,6 +1384,7 @@ pass_cprop_hardreg::execute (function *fun)
   bitmap_clear (visited);
 
   auto_vec<int> worklist;
+  auto_vec<int> third_pass;
   bool any_debug_changes = false;
 
   /* We need accurate notes.  Earlier passes such as if-conversion may
@@ -1425,7 +1426,27 @@ pass_cprop_hardreg::execute (function *fun)
       for (int index : worklist)
 	{
 	  bb = BASIC_BLOCK_FOR_FN (fun, index);
-	  cprop_hardreg_bb (bb, all_vd, visited);
+	  /* Perform a third pass, if the second pass changed anything.
+	     Three passes are required for swaps: t = x; x = y; y = t.  */
+          if (cprop_hardreg_bb (bb, all_vd, visited))
+	    third_pass.safe_push (bb->index);
+	  if (all_vd[bb->index].n_debug_insn_changes)
+	    any_debug_changes = true;
+	}
+
+      df_analyze ();
+      if (MAY_HAVE_DEBUG_BIND_INSNS && any_debug_changes)
+	cprop_hardreg_debug (fun, all_vd);
+    }
+
+  if (!third_pass.is_empty ())
+    {
+      any_debug_changes = false;
+      bitmap_clear (visited);
+      for (int index : third_pass)
+	{
+	  bb = BASIC_BLOCK_FOR_FN (fun, index);
+          cprop_hardreg_bb (bb, all_vd, visited);
 	  if (all_vd[bb->index].n_debug_insn_changes)
 	    any_debug_changes = true;
 	}