Index: lib/CodeGen/RegisterCoalescer.cpp
===================================================================
--- lib/CodeGen/RegisterCoalescer.cpp
+++ lib/CodeGen/RegisterCoalescer.cpp
@@ -1531,6 +1531,14 @@
         DEBUG(dbgs() << "\t\tInterference (read): " << *MI);
         return false;
       }
+
+      // We must also check for clobbers caused by regmasks. We can't use
+      // definesRegister() since it doesn't account for regmasks.
+      for (const auto &MO : MI->operands()) {
+        if (MO.isRegMask() && MO.clobbersPhysReg(DstReg))
+          DEBUG(dbgs() << "\t\tInterference (regmask clobber): " << *MI);
+          return false;
+      }
     }
 
     // We're going to remove the copy which defines a physical reserved