Index: lib/CodeGen/MIRParser/MILexer.h
===================================================================
--- lib/CodeGen/MIRParser/MILexer.h
+++ lib/CodeGen/MIRParser/MILexer.h
@@ -16,6 +16,7 @@
 #define LLVM_LIB_CODEGEN_MIRPARSER_MILEXER_H
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/APSInt.h"
 #include <functional>
 
 namespace llvm {
@@ -35,16 +36,23 @@
 
     // Identifier tokens
     Identifier,
-    NamedRegister
+    NamedRegister,
+
+    // Other tokens
+    IntegerLiteral
   };
 
 private:
   TokenKind Kind;
   StringRef Range;
+  APSInt IntVal;
 
 public:
   MIToken(TokenKind Kind, StringRef Range) : Kind(Kind), Range(Range) {}
 
+  MIToken(TokenKind Kind, StringRef Range, const APSInt &IntVal)
+      : Kind(Kind), Range(Range), IntVal(IntVal) {}
+
   TokenKind kind() const { return Kind; }
 
   bool isError() const { return Kind == Error; }
@@ -58,6 +66,8 @@
   StringRef::iterator location() const { return Range.begin(); }
 
   StringRef stringValue() const { return Range; }
+
+  const APSInt &integerValue() const { return IntVal; }
 };
 
 /// Consume a single machine instruction token in the given source and return
Index: lib/CodeGen/MIRParser/MILexer.cpp
===================================================================
--- lib/CodeGen/MIRParser/MILexer.cpp
+++ lib/CodeGen/MIRParser/MILexer.cpp
@@ -35,6 +35,8 @@
 
   char peek() const { return isEOF() ? 0 : *Ptr; }
 
+  char peekNext() const { return (Ptr + 1) >= End ? 0 : *(Ptr + 1); }
+
   void advance() { ++Ptr; }
 
   StringRef remaining() const { return StringRef(Ptr, End - Ptr); }
@@ -77,6 +79,32 @@
   return C;
 }
 
+static APSInt toInteger(StringRef Str) {
+  assert(!Str.empty() && "Integer literal string must not be empty");
+  unsigned NumBits = ((Str.size() * 64) / 19) + 2;
+  APInt Tmp(NumBits, Str, /*Radix=*/10);
+  if (Str[0] == '-') {
+    unsigned MinBits = Tmp.getMinSignedBits();
+    if (MinBits > 0 && MinBits < NumBits)
+      Tmp = Tmp.trunc(MinBits);
+    return APSInt(Tmp, /*IsUnsigned=*/false);
+  }
+  unsigned ActiveBits = Tmp.getActiveBits();
+  if (ActiveBits > 0 && ActiveBits < NumBits)
+    Tmp = Tmp.trunc(ActiveBits);
+  return APSInt(Tmp, /*IsUnsigned=*/true);
+}
+
+static Cursor lexIntegerLiteral(Cursor C, MIToken &Token) {
+  auto Range = C;
+  C.advance();
+  while (isdigit(C.peek()))
+    C.advance();
+  StringRef StrVal = Range.upto(C);
+  Token = MIToken(MIToken::IntegerLiteral, StrVal, toInteger(StrVal));
+  return C;
+}
+
 static MIToken::TokenKind symbolToken(char C) {
   switch (C) {
   case ',':
@@ -109,6 +137,8 @@
     return lexIdentifier(C, Token).remaining();
   if (Char == '%')
     return lexPercent(C, Token).remaining();
+  if (isdigit(Char) || (Char == '-' && isdigit(C.peekNext())))
+    return lexIntegerLiteral(C, Token).remaining();
   MIToken::TokenKind Kind = symbolToken(Char);
   if (Kind != MIToken::Error)
     return lexSymbol(C, Kind, Token).remaining();
Index: lib/CodeGen/MIRParser/MIParser.cpp
===================================================================
--- lib/CodeGen/MIRParser/MIParser.cpp
+++ lib/CodeGen/MIRParser/MIParser.cpp
@@ -57,6 +57,7 @@
 
   bool parseRegister(unsigned &Reg);
   bool parseRegisterOperand(MachineOperand &Dest, bool IsDef = false);
+  bool parseImmediateOperand(MachineOperand &Dest);
   bool parseMachineOperand(MachineOperand &Dest);
 
 private:
@@ -197,10 +198,23 @@
   return false;
 }
 
+bool MIParser::parseImmediateOperand(MachineOperand &Dest) {
+  assert(Token.is(MIToken::IntegerLiteral));
+  const APSInt &Int = Token.integerValue();
+  if (Int.getMinSignedBits() > 64)
+    // TODO: Replace this with an error when we can parse CIMM Machine Operands.
+    llvm_unreachable("Can't parse large integer literals yet!");
+  Dest = MachineOperand::CreateImm(Int.getExtValue());
+  lex();
+  return false;
+}
+
 bool MIParser::parseMachineOperand(MachineOperand &Dest) {
   switch (Token.kind()) {
   case MIToken::NamedRegister:
     return parseRegisterOperand(Dest);
+  case MIToken::IntegerLiteral:
+    return parseImmediateOperand(Dest);
   case MIToken::Error:
     return true;
   default:
Index: lib/CodeGen/MIRPrinter.cpp
===================================================================
--- lib/CodeGen/MIRPrinter.cpp
+++ lib/CodeGen/MIRPrinter.cpp
@@ -159,6 +159,9 @@
     printReg(Op.getReg(), OS, TRI);
     // TODO: Print sub register.
     break;
+  case MachineOperand::MO_Immediate:
+    OS << Op.getImm();
+    break;
   default:
     // TODO: Print the other machine operands.
     llvm_unreachable("Can't print this machine operand at the moment");
Index: test/CodeGen/MIR/X86/immediate-operands.mir
===================================================================
--- /dev/null
+++ test/CodeGen/MIR/X86/immediate-operands.mir
@@ -0,0 +1,38 @@
+# RUN: llc -march=x86-64 -start-after branch-folder -stop-after branch-folder -o /dev/null %s | FileCheck %s
+# This test ensures that the MIR parser parses immediate machine operands.
+
+--- |
+
+  define i32 @foo() {
+  entry:
+    ret i32 42
+  }
+
+  define i32 @bar() {
+  entry:
+    ret i32 -11
+  }
+
+...
+---
+# CHECK: name: foo
+name:            foo
+body:
+ - name:         entry
+   instructions:
+     # CHECK:      - '%eax = MOV32ri 42'
+     # CHECK-NEXT: - 'RETQ %eax'
+     - '%eax = MOV32ri 42'
+     - 'RETQ %eax'
+...
+---
+# CHECK: name: bar
+name:            bar
+body:
+ - name:         entry
+   instructions:
+     # CHECK:      - '%eax = MOV32ri -11'
+     # CHECK-NEXT: - 'RETQ %eax'
+     - '%eax = MOV32ri -11'
+     - 'RETQ %eax'
+...