Index: llvm/include/llvm/CodeGen/MachineModuleInfo.h
===================================================================
--- llvm/include/llvm/CodeGen/MachineModuleInfo.h
+++ llvm/include/llvm/CodeGen/MachineModuleInfo.h
@@ -83,6 +83,9 @@
 
   /// This is the MCContext used for the entire code generator.
   MCContext Context;
+  // This is an external context, that if assigned, will be used instead of the
+  // internal context.
+  MCContext *ExternalContext = nullptr;
 
   /// This is the LLVM Module being worked on.
   const Module *TheModule;
@@ -149,6 +152,9 @@
 public:
   explicit MachineModuleInfo(const LLVMTargetMachine *TM = nullptr);
 
+  explicit MachineModuleInfo(const LLVMTargetMachine *TM,
+                             MCContext *ExtContext);
+
   MachineModuleInfo(MachineModuleInfo &&MMII);
 
   ~MachineModuleInfo();
@@ -158,8 +164,12 @@
 
   const LLVMTargetMachine &getTarget() const { return TM; }
 
-  const MCContext &getContext() const { return Context; }
-  MCContext &getContext() { return Context; }
+  const MCContext &getContext() const {
+    return ExternalContext ? *ExternalContext : Context;
+  }
+  MCContext &getContext() {
+    return ExternalContext ? *ExternalContext : Context;
+  }
 
   const Module *getModule() const { return TheModule; }
 
@@ -266,6 +276,9 @@
   static char ID; // Pass identification, replacement for typeid
   explicit MachineModuleInfoWrapperPass(const LLVMTargetMachine *TM = nullptr);
 
+  explicit MachineModuleInfoWrapperPass(const LLVMTargetMachine *TM,
+                                        MCContext *ExtContext);
+
   // Initialization and Finalization
   bool doInitialization(Module &) override;
   bool doFinalization(Module &) override;
Index: llvm/lib/CodeGen/MachineModuleInfo.cpp
===================================================================
--- llvm/lib/CodeGen/MachineModuleInfo.cpp
+++ llvm/lib/CodeGen/MachineModuleInfo.cpp
@@ -170,6 +170,7 @@
   AddrLabelSymbols = nullptr;
 
   Context.reset();
+  // We don't clear the ExternalContext.
 
   delete ObjFileMMI;
   ObjFileMMI = nullptr;
@@ -187,6 +188,7 @@
   HasSplitStack = MMI.HasSplitStack;
   HasNosplitStack = MMI.HasNosplitStack;
   AddrLabelSymbols = MMI.AddrLabelSymbols;
+  ExternalContext = MMI.ExternalContext;
   TheModule = MMI.TheModule;
 }
 
@@ -196,6 +198,14 @@
   initialize();
 }
 
+MachineModuleInfo::MachineModuleInfo(const LLVMTargetMachine *TM,
+                                     MCContext *ExtContext)
+    : TM(*TM), Context(TM->getMCAsmInfo(), TM->getMCRegisterInfo(),
+                       TM->getObjFileLowering(), nullptr, nullptr, false),
+      ExternalContext(ExtContext) {
+  initialize();
+}
+
 MachineModuleInfo::~MachineModuleInfo() { finalize(); }
 
 //===- Address of Block Management ----------------------------------------===//
@@ -204,7 +214,7 @@
 MachineModuleInfo::getAddrLabelSymbolToEmit(const BasicBlock *BB) {
   // Lazily create AddrLabelSymbols.
   if (!AddrLabelSymbols)
-    AddrLabelSymbols = new MMIAddrLabelMap(Context);
+    AddrLabelSymbols = new MMIAddrLabelMap(getContext());
  return AddrLabelSymbols->getAddrLabelSymbolToEmit(const_cast<BasicBlock*>(BB));
 }
 
@@ -296,6 +306,12 @@
   initializeMachineModuleInfoWrapperPassPass(*PassRegistry::getPassRegistry());
 }
 
+MachineModuleInfoWrapperPass::MachineModuleInfoWrapperPass(
+    const LLVMTargetMachine *TM, MCContext *ExtContext)
+    : ImmutablePass(ID), MMI(TM, ExtContext) {
+  initializeMachineModuleInfoWrapperPassPass(*PassRegistry::getPassRegistry());
+}
+
 // Handle the Pass registration stuff necessary to use DataLayout's.
 INITIALIZE_PASS(MachineModuleInfoWrapperPass, "machinemoduleinfo",
                 "Machine Module Information", false, false)