Index: include/llvm/CodeGen/RegisterMIRPasses.h
===================================================================
--- /dev/null
+++ include/llvm/CodeGen/RegisterMIRPasses.h
@@ -0,0 +1,17 @@
+#ifndef LLVM_REGISTER_MACHINE_PASS_H
+#define LLVM_REGISTER_MACHINE_PASS_H
+
+#include "llvm/CodeGen/TargetPassConfig.h"
+
+namespace llvm {
+  
+struct RegisterMIRPasses {
+  RegisterMIRPasses(TargetPassConfig::ExtensionPointTy Ty, 
+                    TargetPassConfig::ExtensionFn Fn) {
+    TargetPassConfig::addGlobalExtension(Ty, Fn);
+  }
+};
+
+} // llvm
+
+#endif
Index: include/llvm/CodeGen/TargetPassConfig.h
===================================================================
--- include/llvm/CodeGen/TargetPassConfig.h
+++ include/llvm/CodeGen/TargetPassConfig.h
@@ -15,6 +15,7 @@
 
 #include "llvm/Pass.h"
 #include "llvm/Support/CodeGen.h"
+#include "llvm/ADT/DenseMap.h"
 #include <cassert>
 #include <string>
 
@@ -81,7 +82,32 @@
 /// This is an ImmutablePass solely for the purpose of exposing CodeGen options
 /// to the internals of other CodeGen passes.
 class TargetPassConfig : public ImmutablePass {
+public:
+  typedef void(*ExtensionFn)(const TargetPassConfig& Builder,
+                             legacy::PassManagerBase &PM);
+
+  enum ExtensionPointTy {
+    /// This extension point allows adding passes before
+    /// any other transformations.
+    EP_EarlyAsPossible,
+
+    /// This extension point allows adding passes before register allocation.
+    EP_BeforeRA,
+    /// This extension point allows adding passes after register allocation.
+    EP_AfterRA,
+    /// This extension point allows adding passes that / run after everything
+    //else.
+    EP_OptimizerLast,
+  };
+  static constexpr size_t EP_EnumSize = EP_OptimizerLast+1;
+
+  static void addGlobalExtension(ExtensionPointTy Ty, ExtensionFn Fn);
+  void addExtension(ExtensionPointTy Ty, ExtensionFn Fn);
+  void addExtensionsToPM(ExtensionPointTy ETy) const;
+
 private:
+  SmallVector<ExtensionFn,4> Extensions[EP_EnumSize];
+
   PassManagerBase *PM = nullptr;
   AnalysisID StartBefore = nullptr;
   AnalysisID StartAfter = nullptr;
Index: lib/CodeGen/TargetPassConfig.cpp
===================================================================
--- lib/CodeGen/TargetPassConfig.cpp
+++ lib/CodeGen/TargetPassConfig.cpp
@@ -203,6 +203,31 @@
                   cl::desc("Stop compilation before a specific pass"),
                   cl::value_desc("pass-name"), cl::init(""), cl::Hidden);
 
+static ManagedStatic<std::array<SmallVector<TargetPassConfig::ExtensionFn,4>,
+  TargetPassConfig::EP_EnumSize>> GlobalExtensions;
+
+void TargetPassConfig::addGlobalExtension(
+    TargetPassConfig::ExtensionPointTy Ty,
+    TargetPassConfig::ExtensionFn Fn) {
+  (*GlobalExtensions)[Ty].push_back(Fn);
+}
+
+void TargetPassConfig::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
+  Extensions[Ty].push_back(Fn);
+}
+
+void TargetPassConfig::addExtensionsToPM(ExtensionPointTy ETy) const {
+  if (GlobalExtensions.isConstructed()) {
+    for (auto Fn: (*GlobalExtensions)[ETy]) {
+      Fn(*this, *PM);
+    }
+  }
+  for (auto Fn: Extensions[ETy]) {
+    Fn(*this, *PM);
+  }
+}
+
+
 /// Allow standard passes to be disabled by command line options. This supports
 /// simple binary flags that either suppress the pass or do nothing.
 /// i.e. -disable-mypass=false has no effect.
@@ -884,6 +909,8 @@
     }
   }
 
+  addExtensionsToPM(EP_EarlyAsPossible);
+
   // Add passes that optimize machine instructions in SSA form.
   if (getOptLevel() != CodeGenOpt::None) {
     addMachineSSAOptimization();
@@ -896,6 +923,8 @@
   if (TM->Options.EnableIPRA)
     addPass(createRegUsageInfoPropPass());
 
+  addExtensionsToPM(EP_BeforeRA);
+
   // Run pre-ra passes.
   addPreRegAlloc();
 
@@ -909,6 +938,8 @@
   // Run post-ra passes.
   addPostRegAlloc();
 
+  addExtensionsToPM(EP_AfterRA);
+
   // Insert prolog/epilog code.  Eliminate abstract frame index references...
   if (getOptLevel() != CodeGenOpt::None) {
     addPass(&PostRAMachineSinkingID);
@@ -984,6 +1015,8 @@
   // Add passes that directly emit MI after all other MI passes.
   addPreEmitPass2();
 
+  addExtensionsToPM(EP_OptimizerLast);
+
   AddingMachinePasses = false;
 }