Index: llvm/include/llvm/IR/Module.h
===================================================================
--- llvm/include/llvm/IR/Module.h
+++ llvm/include/llvm/IR/Module.h
@@ -403,16 +403,23 @@
   }
 
   /// Look up the specified global in the module symbol table.
-  ///   1. If it does not exist, add a declaration of the global and return it.
+  ///   1. If it does not exist, invoke to callback to a declaration of the
+  ///      global and return it.
   ///   2. Else, the global exists but has the wrong type: return the function
   ///      with a constantexpr cast to the right type.
-  ///   3. Finally, if the existing global is the correct declaration, return
+  ///   3. Finally, if the existing global has the correct type, return
   ///      the existing global.
+  Constant *
+  getOrInsertGlobal(StringRef Name, Type *Ty,
+                    function_ref<GlobalVariable *()> CreateGlobalCallback);
+
+  /// Look up the specified global in the module symbol table. If required, this
+  /// overload constructs the global variable using its constructor's defaults.
   Constant *getOrInsertGlobal(StringRef Name, Type *Ty);
 
-/// @}
-/// @name Global Alias Accessors
-/// @{
+  /// @}
+  /// @name Global Alias Accessors
+  /// @{
 
   /// Return the global alias in the module with the specified name, of
   /// arbitrary type. This method returns null if a global with the specified
Index: llvm/lib/IR/Module.cpp
===================================================================
--- llvm/lib/IR/Module.cpp
+++ llvm/lib/IR/Module.cpp
@@ -203,16 +203,13 @@
 ///      with a constantexpr cast to the right type.
 ///   3. Finally, if the existing global is the correct declaration, return the
 ///      existing global.
-Constant *Module::getOrInsertGlobal(StringRef Name, Type *Ty) {
+Constant *Module::getOrInsertGlobal(
+    StringRef Name, Type *Ty,
+    function_ref<GlobalVariable *()> CreateGlobalCallback) {
   // See if we have a definition for the specified global already.
   GlobalVariable *GV = dyn_cast_or_null<GlobalVariable>(getNamedValue(Name));
-  if (!GV) {
-    // Nope, add it
-    GlobalVariable *New =
-      new GlobalVariable(*this, Ty, false, GlobalVariable::ExternalLinkage,
-                         nullptr, Name);
-     return New;                    // Return the new declaration.
-  }
+  if (!GV)
+    return CreateGlobalCallback();
 
   // If the variable exists but has the wrong type, return a bitcast to the
   // right type.
@@ -225,6 +222,14 @@
   return GV;
 }
 
+// Overload to construct a global variable using its constructor's defaults.
+Constant *Module::getOrInsertGlobal(StringRef Name, Type *Ty) {
+  return getOrInsertGlobal(Name, Ty, [=] {
+    return new GlobalVariable(*this, Ty, false, GlobalVariable::ExternalLinkage,
+                              nullptr, Name);
+  });
+}
+
 //===----------------------------------------------------------------------===//
 // Methods for easy access to the global variables in the module.
 //