Index: include/llvm/CodeGen/BasicTTIImpl.h
===================================================================
--- include/llvm/CodeGen/BasicTTIImpl.h
+++ include/llvm/CodeGen/BasicTTIImpl.h
@@ -281,7 +281,11 @@
 
     // Enable runtime and partial unrolling up to the specified size.
     UP.Partial = UP.Runtime = true;
-    UP.PartialThreshold = UP.PartialOptSizeThreshold = MaxOps;
+    UP.PartialThreshold = MaxOps;
+
+    // Avoid unrolling when optimizing for size.
+    UP.OptSizeThreshold = 0;
+    UP.PartialOptSizeThreshold = 0;
   }
 
   /// @}
Index: lib/Transforms/Scalar/LoopUnrollPass.cpp
===================================================================
--- lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -948,6 +948,10 @@
       L, TTI, ProvidedThreshold, ProvidedCount, ProvidedAllowPartial,
       ProvidedRuntime);
 
+  // Exit early if unrolling is disabled.
+  if (UP.Threshold == 0 && UP.PartialThreshold == 0)
+    return false;
+
   // If the loop contains a convergent operation, the prelude we'd add
   // to do the first few instructions before we hit the unrolled loop
   // is unsafe -- it adds a control-flow dependency to the convergent