Index: llvm/lib/FuzzMutate/IRMutator.cpp
===================================================================
--- llvm/lib/FuzzMutate/IRMutator.cpp
+++ llvm/lib/FuzzMutate/IRMutator.cpp
@@ -143,7 +143,10 @@
     return CurrentWeight ? CurrentWeight * 100 : 1;
   // Draw a line starting from when we only have 1k left and increasing linearly
   // to double the current weight.
-  int Line = (-2 * CurrentWeight) * (MaxSize - CurrentSize + 1000);
+  int64_t Line = (-2 * static_cast<int64_t>(CurrentWeight)) *
+                 (static_cast<int64_t>(MaxSize) -
+                  static_cast<int64_t>(CurrentSize) - 1000) /
+                 1000;
   // Clamp negative weights to zero.
   if (Line < 0)
     return 0;