Index: include/polly/Support/ScopHelper.h
===================================================================
--- include/polly/Support/ScopHelper.h
+++ include/polly/Support/ScopHelper.h
@@ -164,5 +164,14 @@
 ///         otherwise return false.
 bool canSynthesize(const llvm::Value *V, const llvm::LoopInfo *LI,
                    llvm::ScalarEvolution *SE, const llvm::Region *R);
+
+/// @brief Return the block in which a value is used.
+///
+/// For normal instructions, this is the instruction's parent block. For PHI
+/// nodes, this is the incoming block of that use, because this is where the
+/// operand must be defined (i.e. its definition dominates this block).
+/// Non-instructions do not use operands at a specific point such that in this
+/// case this function returns nullptr.
+llvm::BasicBlock *getUseBlock(llvm::Use &U);
 }
 #endif
Index: lib/CodeGen/BlockGenerators.cpp
===================================================================
--- lib/CodeGen/BlockGenerators.cpp
+++ lib/CodeGen/BlockGenerators.cpp
@@ -365,14 +365,14 @@
     return;
 
   EscapeUserVectorTy EscapeUsers;
-  for (User *U : Inst->users()) {
+  for (Use &U : Inst->uses()) {
 
     // Non-instruction user will never escape.
-    Instruction *UI = dyn_cast<Instruction>(U);
+    Instruction *UI = dyn_cast<Instruction>(U.getUser());
     if (!UI)
       continue;
 
-    if (R.contains(UI))
+    if (R.contains(getUseBlock(U)))
       continue;
 
     EscapeUsers.push_back(UI);
Index: lib/Support/ScopHelper.cpp
===================================================================
--- lib/Support/ScopHelper.cpp
+++ lib/Support/ScopHelper.cpp
@@ -453,3 +453,14 @@
 
   return false;
 }
+
+llvm::BasicBlock *polly::getUseBlock(llvm::Use &U) {
+  Instruction *UI = dyn_cast<Instruction>(U.getUser());
+  if (!UI)
+    return nullptr;
+
+  if (PHINode *PHI = dyn_cast<PHINode>(UI))
+    return PHI->getIncomingBlock(U);
+
+  return UI->getParent();
+}