diff --git a/include/llvm/MC/MCParser/MCAsmLexer.h b/include/llvm/MC/MCParser/MCAsmLexer.h
index 8edf3a4423f..ceba3f05e1c 100644
--- a/include/llvm/MC/MCParser/MCAsmLexer.h
+++ b/include/llvm/MC/MCParser/MCAsmLexer.h
@@ -10,6 +10,7 @@
 #ifndef LLVM_MC_MCPARSER_MCASMLEXER_H
 #define LLVM_MC_MCPARSER_MCASMLEXER_H
 
+#include "llvm/ADT/APInt.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
@@ -30,6 +31,7 @@ public:
 
     // Integer values.
     Integer,
+    BigNum, // larger than 64 bits
 
     // Real values.
     Real,
@@ -57,12 +59,14 @@ private:
   /// a memory buffer owned by the source manager.
   StringRef Str;
 
-  int64_t IntVal;
+  APInt IntVal;
 
 public:
   AsmToken() {}
-  AsmToken(TokenKind _Kind, StringRef _Str, int64_t _IntVal = 0)
+  AsmToken(TokenKind _Kind, StringRef _Str, APInt _IntVal)
     : Kind(_Kind), Str(_Str), IntVal(_IntVal) {}
+  AsmToken(TokenKind _Kind, StringRef _Str, int64_t _IntVal = 0)
+    : Kind(_Kind), Str(_Str), IntVal(64, _IntVal, true) {}
 
   TokenKind getKind() const { return Kind; }
   bool is(TokenKind K) const { return Kind == K; }
@@ -99,6 +103,12 @@ public:
   // as a single token, then diagnose as an invalid number).
   int64_t getIntVal() const {
     assert(Kind == Integer && "This token isn't an integer!");
+    return IntVal.getZExtValue();
+  }
+
+  APInt getAPIntVal() const {
+    assert((Kind == Integer || Kind == BigNum) &&
+           "This token isn't an integer!");
     return IntVal;
   }
 };
diff --git a/lib/MC/MCParser/AsmLexer.cpp b/lib/MC/MCParser/AsmLexer.cpp
index ed98f93758e..88f17617895 100644
--- a/lib/MC/MCParser/AsmLexer.cpp
+++ b/lib/MC/MCParser/AsmLexer.cpp
@@ -238,6 +238,13 @@ static unsigned doLookAhead(const char *&CurPtr, unsigned DefaultRadix) {
   return DefaultRadix;
 }
 
+static AsmToken intToken(StringRef Ref, APInt &Value)
+{
+  if (Value.isIntN(64))
+    return AsmToken(AsmToken::Integer, Ref, Value);
+  return AsmToken(AsmToken::BigNum, Ref, Value);
+}
+
 /// LexDigit: First character is [0-9].
 ///   Local Label: [0-9][:]
 ///   Forward/Backward Label: [0-9][fb]
@@ -258,16 +265,10 @@ AsmToken AsmLexer::LexDigit() {
 
     StringRef Result(TokStart, CurPtr - TokStart);
 
-    long long Value;
-    if (Result.getAsInteger(Radix, Value)) {
-      // Allow positive values that are too large to fit into a signed 64-bit
-      // integer, but that do fit in an unsigned one, we just convert them over.
-      unsigned long long UValue;
-      if (Result.getAsInteger(Radix, UValue))
-        return ReturnError(TokStart, !isHex ? "invalid decimal number" :
+    APInt Value(128, 0, true);
+    if (Result.getAsInteger(Radix, Value))
+      return ReturnError(TokStart, !isHex ? "invalid decimal number" :
                            "invalid hexdecimal number");
-      Value = (long long)UValue;
-    }
 
     // Consume the [bB][hH].
     if (Radix == 2 || Radix == 16)
@@ -277,7 +278,7 @@ AsmToken AsmLexer::LexDigit() {
     // suffices on integer literals.
     SkipIgnoredIntegerSuffix(CurPtr);
 
-    return AsmToken(AsmToken::Integer, Result, Value);
+    return intToken(Result, Value);
   }
 
   if (*CurPtr == 'b') {
@@ -298,7 +299,7 @@ AsmToken AsmLexer::LexDigit() {
 
     StringRef Result(TokStart, CurPtr - TokStart);
 
-    long long Value;
+    APInt Value(128, 0, true);
     if (Result.substr(2).getAsInteger(2, Value))
       return ReturnError(TokStart, "invalid binary number");
 
@@ -306,7 +307,7 @@ AsmToken AsmLexer::LexDigit() {
     // suffixes on integer literals.
     SkipIgnoredIntegerSuffix(CurPtr);
 
-    return AsmToken(AsmToken::Integer, Result, Value);
+    return intToken(Result, Value);
   }
 
   if (*CurPtr == 'x') {
@@ -324,7 +325,7 @@ AsmToken AsmLexer::LexDigit() {
     if (CurPtr == NumStart)
       return ReturnError(CurPtr-2, "invalid hexadecimal number");
 
-    unsigned long long Result;
+    APInt Result(128, 0);
     if (StringRef(TokStart, CurPtr - TokStart).getAsInteger(0, Result))
       return ReturnError(TokStart, "invalid hexadecimal number");
 
@@ -336,12 +337,11 @@ AsmToken AsmLexer::LexDigit() {
     // suffixes on integer literals.
     SkipIgnoredIntegerSuffix(CurPtr);
 
-    return AsmToken(AsmToken::Integer, StringRef(TokStart, CurPtr - TokStart),
-                    (int64_t)Result);
+    return intToken(StringRef(TokStart, CurPtr - TokStart), Result);
   }
 
   // Either octal or hexadecimal.
-  long long Value;
+  APInt Value(128, 0, true);
   unsigned Radix = doLookAhead(CurPtr, 8);
   bool isHex = Radix == 16;
   StringRef Result(TokStart, CurPtr - TokStart);
@@ -357,7 +357,7 @@ AsmToken AsmLexer::LexDigit() {
   // suffixes on integer literals.
   SkipIgnoredIntegerSuffix(CurPtr);
 
-  return AsmToken(AsmToken::Integer, Result, Value);
+  return intToken(Result, Value);
 }
 
 /// LexSingleQuote: Integer: 'b'
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 9157ac4f67c..e236c170b79 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -854,6 +854,8 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
     Res = MCSymbolRefExpr::Create(Sym, Variant, getContext());
     return false;
   }
+  case AsmToken::BigNum:
+    return TokError("literal value out of range for directive");
   case AsmToken::Integer: {
     SMLoc Loc = getTok().getLoc();
     int64_t IntVal = getTok().getIntVal();