diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2126,12 +2126,16 @@
 
 DebugLoc DwarfDebug::emitInitialLocDirective(const MachineFunction &MF,
                                              unsigned CUID) {
+  // If we have code without debug information we need to give up.
+  DISubprogram *MFSP = MF.getFunction().getSubprogram();
+  if (!MFSP)
+    return DebugLoc();
+
   // Get beginning of function.
   if (DebugLoc PrologEndLoc = findPrologueEndLoc(&MF)) {
     // Ensure the compile unit is created if the function is called before
     // beginFunction().
-    (void)getOrCreateDwarfCompileUnit(
-        MF.getFunction().getSubprogram()->getUnit());
+    (void)getOrCreateDwarfCompileUnit(MFSP->getUnit());
     // We'd like to list the prologue as "not statements" but GDB behaves
     // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
     const DISubprogram *SP = PrologEndLoc->getInlinedAtScope()->getSubprogram();