diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index fcc4993..4bb50a3 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -79,7 +79,6 @@
 
 namespace CodeGen {
 
-class BlockByrefHelpers;
 class CallArgList;
 class CodeGenFunction;
 class CodeGenTBAA;
@@ -210,6 +209,36 @@
   void reportDiagnostics(DiagnosticsEngine &Diags, StringRef MainFile);
 };
 
+/// A pair of helper functions for a __block variable.
+class BlockByrefHelpers : public llvm::FoldingSetNode {
+  // MSVC requires this type to be complete in order to process this
+  // header.
+public:
+  llvm::Constant *CopyHelper;
+  llvm::Constant *DisposeHelper;
+
+  /// The alignment of the field.  This is important because
+  /// different offsets to the field within the byref struct need to
+  /// have different helper functions.
+  CharUnits Alignment;
+
+  BlockByrefHelpers(CharUnits alignment) : Alignment(alignment) {}
+  BlockByrefHelpers(const BlockByrefHelpers &) = default;
+  virtual ~BlockByrefHelpers();
+
+  void Profile(llvm::FoldingSetNodeID &id) const {
+    id.AddInteger(Alignment.getQuantity());
+    profileImpl(id);
+  }
+  virtual void profileImpl(llvm::FoldingSetNodeID &id) const = 0;
+
+  virtual bool needsCopy() const { return true; }
+  virtual void emitCopy(CodeGenFunction &CGF, Address dest, Address src) = 0;
+
+  virtual bool needsDispose() const { return true; }
+  virtual void emitDispose(CodeGenFunction &CGF, Address field) = 0;
+};
+
 /// This class organizes the cross-function state that is used while generating
 /// LLVM code.
 class CodeGenModule : public CodeGenTypeCache {