Index: lib/IR/BasicBlock.cpp
===================================================================
--- lib/IR/BasicBlock.cpp
+++ lib/IR/BasicBlock.cpp
@@ -264,7 +264,12 @@
 }
 
 iterator_range<BasicBlock::phi_iterator> BasicBlock::phis() {
-  return make_range<phi_iterator>(dyn_cast<PHINode>(&front()), nullptr);
+  PHINode *P = nullptr;
+  auto I = begin();
+  if (I != end())
+    P = dyn_cast<PHINode>(&*I);
+
+  return make_range<phi_iterator>(P, nullptr);
 }
 
 /// This method is used to notify a BasicBlock that the