Index: llvm/include/llvm/CodeGen/MachineInstr.h
===================================================================
--- llvm/include/llvm/CodeGen/MachineInstr.h
+++ llvm/include/llvm/CodeGen/MachineInstr.h
@@ -282,6 +282,13 @@
   /// defined by this instruction.
   unsigned DebugInstrNum;
 
+#ifndef NDEBUG
+  unsigned UID;
+  static unsigned NextUID;
+#endif
+
+  void setUID();
+
   // Intrusive list support
   friend struct ilist_traits<MachineInstr>;
   friend struct ilist_callback_traits<MachineBasicBlock>;
Index: llvm/include/llvm/IR/Value.h
===================================================================
--- llvm/include/llvm/IR/Value.h
+++ llvm/include/llvm/IR/Value.h
@@ -121,6 +121,14 @@
   unsigned HasDescriptor : 1;
 
 private:
+
+#ifndef NDEBUG
+  unsigned UID;
+  static unsigned NextUID;
+#endif
+
+  void setUID();
+
   template <typename UseT> // UseT == 'Use' or 'const Use'
   class use_iterator_impl {
     friend class Value;
@@ -225,6 +233,11 @@
   Value(const Value &) = delete;
   Value &operator=(const Value &) = delete;
 
+#ifndef NDEBUG
+  /// Returns unique ID of Value
+  unsigned getUID() const { return UID; }
+#endif
+
   /// Delete a pointer to a generic Value.
   void deleteValue();
 
Index: llvm/lib/CodeGen/MachineInstr.cpp
===================================================================
--- llvm/lib/CodeGen/MachineInstr.cpp
+++ llvm/lib/CodeGen/MachineInstr.cpp
@@ -60,6 +60,8 @@
 
 using namespace llvm;
 
+extern cl::opt<bool> PrintUIDs;
+
 static const MachineFunction *getMFIfAvailable(const MachineInstr &MI) {
   if (const MachineBasicBlock *MBB = MI.getParent())
     if (const MachineFunction *MF = MBB->getParent())
@@ -107,6 +109,8 @@
 
   if (!NoImp)
     addImplicitDefUseOperands(MF);
+
+  setUID();
 }
 
 /// MachineInstr ctor - Copies MachineInstr arg exactly.
@@ -134,8 +138,19 @@
 
   // Copy all the sensible flags.
   setFlags(MI.Flags);
+
+  setUID();
+}
+
+void MachineInstr::setUID() {
+#ifndef NDEBUG
+  UID = NextUID;
+  ++NextUID;
+#endif
 }
 
+unsigned MachineInstr::NextUID;
+
 void MachineInstr::moveBefore(MachineInstr *MovePos) {
   MovePos->getParent()->splice(MovePos, getParent(), getIterator());
 }
@@ -1883,6 +1898,16 @@
   }
   // TODO: DBG_LABEL
 
+  if (PrintUIDs) {
+#ifndef NDEBUG
+    if (!HaveSemi) {
+      OS << ";";
+      HaveSemi = true;
+    }
+    OS << " UID:" << UID;
+#endif
+  }
+
   if (AddNewLine)
     OS << '\n';
 }
Index: llvm/lib/IR/AsmWriter.cpp
===================================================================
--- llvm/lib/IR/AsmWriter.cpp
+++ llvm/lib/IR/AsmWriter.cpp
@@ -88,6 +88,9 @@
 
 using namespace llvm;
 
+cl::opt<bool> PrintUIDs("print-uids", cl::Hidden, cl::init(false),
+                        cl::desc("Print instruction IDs in IR dumps"));
+
 // Make virtual table appear in this compilation unit.
 AssemblyAnnotationWriter::~AssemblyAnnotationWriter() = default;
 
@@ -4007,6 +4010,13 @@
 
   if (AnnotationWriter)
     AnnotationWriter->printInfoComment(V, Out);
+
+  if (PrintUIDs) {
+#ifndef NDEBUG
+    Out << " ; UID:";
+    Out << V.getUID();
+#endif
+  }
 }
 
 static void maybePrintCallAddrSpace(const Value *Operand, const Instruction *I,
Index: llvm/lib/IR/Value.cpp
===================================================================
--- llvm/lib/IR/Value.cpp
+++ llvm/lib/IR/Value.cpp
@@ -68,8 +68,15 @@
            (/*SubclassID < ConstantFirstVal ||*/ SubclassID > ConstantLastVal))
     assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
            "Cannot create non-first-class values except for constants!");
-  static_assert(sizeof(Value) == 2 * sizeof(void *) + 2 * sizeof(unsigned),
+#ifdef NDEBUG
+  constexpr bool HasUID = false;
+#else
+  constexpr bool HasUID = true;
+#endif
+  static_assert(sizeof(Value) == 2 * sizeof(void *) + 2 * sizeof(unsigned) +
+                                     (HasUID ? sizeof(void *) : 0),
                 "Value too big");
+  setUID();
 }
 
 Value::~Value() {
@@ -106,6 +113,15 @@
   destroyValueName();
 }
 
+void Value::setUID() {
+#ifndef NDEBUG
+  UID = NextUID;
+  ++NextUID;
+#endif
+}
+
+unsigned Value::NextUID;
+
 void Value::deleteValue() {
   switch (getValueID()) {
 #define HANDLE_VALUE(Name)                                                     \