Index: include/llvm/Support/MathExtras.h
===================================================================
--- include/llvm/Support/MathExtras.h
+++ include/llvm/Support/MathExtras.h
@@ -252,6 +252,12 @@
   return static_cast<uint32_t>(Value);
 }
 
+/// Lo_Bits - This function returns the low \p Bits bits of Value.
+inline uint64_t Lo_Bits(uint64_t Value, unsigned Bits) {
+  assert(Bits <= 64);
+  return Value & (~0ULL >> (64 - Bits));
+}
+
 /// Make_64 - This functions makes a 64-bit integer from a high / low pair of
 ///           32-bit integers.
 inline uint64_t Make_64(uint32_t High, uint32_t Low) {
Index: tools/dsymutil/DwarfLinker.cpp
===================================================================
--- tools/dsymutil/DwarfLinker.cpp
+++ tools/dsymutil/DwarfLinker.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Object/MachO.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/LEB128.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
@@ -838,8 +839,10 @@
         Asm->OutStreamer->EmitIntValue(0, AddressSize);
         break;
       }
-      Asm->OutStreamer->EmitIntValue(Low + LocPcOffset, AddressSize);
-      Asm->OutStreamer->EmitIntValue(High + LocPcOffset, AddressSize);
+      Asm->OutStreamer->EmitIntValue(
+          llvm::Lo_Bits(Low + LocPcOffset, 8 * AddressSize), AddressSize);
+      Asm->OutStreamer->EmitIntValue(
+          llvm::Lo_Bits(High + LocPcOffset, 8 * AddressSize), AddressSize);
       uint64_t Length = Data.getU16(&Offset);
       Asm->OutStreamer->EmitIntValue(Length, 2);
       // Just copy the bytes over.