Index: include/llvm/Support/Dwarf.h
===================================================================
--- include/llvm/Support/Dwarf.h
+++ include/llvm/Support/Dwarf.h
@@ -21,6 +21,8 @@
 
 namespace llvm {
 
+class Module;
+
 //===----------------------------------------------------------------------===//
 // Debug info constants.
 
@@ -951,6 +953,9 @@
   };
 };
 
+/// Return Dwarf Version by checking module flags.
+unsigned getDwarfVersionFromModule(const Module *M);
+
 } // End of namespace dwarf
 
 } // End of namespace llvm
Index: lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -168,14 +168,6 @@
 
 } // end llvm namespace
 
-/// Return Dwarf Version by checking module flags.
-static unsigned getDwarfVersionFromModule(const Module *M) {
-  Value *Val = M->getModuleFlag("Dwarf Version");
-  if (!Val)
-    return dwarf::DWARF_VERSION;
-  return cast<ConstantInt>(Val)->getZExtValue();
-}
-
 DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
     : Asm(A), MMI(Asm->MMI), FirstCU(0), PrevLabel(NULL), GlobalRangeCount(0),
       InfoHolder(A, "info_string", DIEValueAllocator),
@@ -211,7 +203,7 @@
 
   DwarfVersion = DwarfVersionNumber
                      ? DwarfVersionNumber
-                     : getDwarfVersionFromModule(MMI->getModule());
+                     : dwarf::getDwarfVersionFromModule(MMI->getModule());
 
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
Index: lib/Support/Dwarf.cpp
===================================================================
--- lib/Support/Dwarf.cpp
+++ lib/Support/Dwarf.cpp
@@ -13,6 +13,8 @@
 
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Constants.h"
 
 using namespace llvm;
 using namespace dwarf;
@@ -795,3 +797,10 @@
   }
   llvm_unreachable("Unknown GDBIndexEntryLinkage value");
 }
+
+unsigned getDwarfVersionFromModule(const Module *M) {
+  Value *Val = M->getModuleFlag("Dwarf Version");
+  if (!Val)
+    return llvm::dwarf::DWARF_VERSION;
+  return cast<ConstantInt>(Val)->getZExtValue();
+}
Index: lib/Transforms/Utils/AddDiscriminators.cpp
===================================================================
--- lib/Transforms/Utils/AddDiscriminators.cpp
+++ lib/Transforms/Utils/AddDiscriminators.cpp
@@ -65,6 +65,7 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Dwarf.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -157,7 +158,12 @@
   // No need to do anything if there is no debug info for this function.
   // If the function has debug information, but the user has disabled
   // discriminators, do nothing.
-  if (!hasDebugInfo(F) || NoDiscriminators) return false;
+  // Finally, if this module is built with dwarf versions earlier than 4,
+  // do nothing (discriminator support is a DWARF 4 feature).
+  if (!hasDebugInfo(F) ||
+      dwarf::getDwarfVersionFromModule(F.getParent()) < 4 ||
+      NoDiscriminators)
+    return false;
 
   bool Changed = false;
   Module *M = F.getParent();