Index: lib/Transforms/IPO/Inliner.cpp
===================================================================
--- lib/Transforms/IPO/Inliner.cpp
+++ lib/Transforms/IPO/Inliner.cpp
@@ -296,6 +296,17 @@
   if (InlineHint && HintThreshold > Threshold &&
       !Caller->hasFnAttribute(Attribute::MinSize))
     Threshold = HintThreshold;
+  // If profile information is available, use that to prioritize hot functions.
+  // FIXME: The heuristic used here is based on preliminary SPEC tuning and
+  // may not be optimal. Replace this with a well-tuned heuristic based on
+  // *callsite* hotness and not callee hotness.
+  auto EntryCount = Callee->getEntryCount();
+  auto MaxFunctionCount = Callee->getParent()->getMaximumFunctionCount();
+  if (EntryCount && MaxFunctionCount &&
+      EntryCount.getValue() >=
+          (uint64_t)(0.3 * (double)MaxFunctionCount.getValue())) {
+    Threshold = HintThreshold;
+  }
 
   // Listen to the cold attribute when it would decrease the threshold.
   bool ColdCallee = Callee && !Callee->isDeclaration() &&