Index: lib/Analysis/ValueTracking.cpp
===================================================================
--- lib/Analysis/ValueTracking.cpp
+++ lib/Analysis/ValueTracking.cpp
@@ -3126,6 +3126,12 @@
       case Intrinsic::minnum:
       case Intrinsic::maxnum:
         return true;
+      // These intrinsics are defined to have the same behavior as libm
+      // functions, which never overflow when operating on the IEEE754 types
+      // that we support.
+      case Intrinsic::round:
+      case Intrinsic::rint:
+        return true;
       // TODO: some fp intrinsics are marked as having the same error handling
       // as libm. They're safe to speculate when they won't error.
       // TODO: are convert_{from,to}_fp16 safe?