diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index b9910c35bad..ccadac0cd8e 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2042,10 +2042,18 @@ bool DwarfDebug::extractScopeInformation(MachineFunction *MF) {
   // Each scope has first instruction and last instruction to mark beginning
   // and end of a scope respectively. Create an inverse map that list scopes
   // starts (and ends) with an instruction. One instruction may start (or end)
-  // multiple scopes.
-  for (DenseMap<MDNode *, DbgScope *>::iterator DI = DbgScopeMap.begin(),
-	 DE = DbgScopeMap.end(); DI != DE; ++DI) {
-    DbgScope *S = DI->second;
+  // multiple scopes. Ignore scopes that are not reachable.
+  SmallVector<DbgScope *, 4> WorkList;
+  WorkList.push_back(CurrentFnDbgScope);
+  while (!WorkList.empty()) {
+    DbgScope *S = WorkList.back(); WorkList.pop_back();
+
+    SmallVector<DbgScope *, 4> &Children = S->getScopes();
+    if (!Children.empty()) 
+      for (SmallVector<DbgScope *, 4>::iterator SI = Children.begin(),
+             SE = Children.end(); SI != SE; ++SI)
+        WorkList.push_back(*SI);
+
     if (S->isAbstractScope())
       continue;
     const MachineInstr *MI = S->getFirstInsn();
diff --git a/test/DebugInfo/2010-01-19-DbgScope.ll b/test/DebugInfo/2010-01-19-DbgScope.ll
new file mode 100644
index 00000000000..7afb5a500fb
--- /dev/null
+++ b/test/DebugInfo/2010-01-19-DbgScope.ll
@@ -0,0 +1,28 @@
+; RUN: llc -O0 < %s -o /dev/null
+; Ignore unreachable scopes.
+declare void @foo(i32) noreturn
+
+define i32 @bar() nounwind ssp {
+entry:
+  br i1 undef, label %bb, label %bb11, !dbg !0
+
+bb:                                               ; preds = %entry
+  call void @foo(i32 0) noreturn nounwind, !dbg !7
+  unreachable, !dbg !7
+
+bb11:                                             ; preds = %entry
+  ret i32 1, !dbg !11
+}
+
+!0 = metadata !{i32 8647, i32 0, metadata !1, null}
+!1 = metadata !{i32 458763, metadata !2}          ; [ DW_TAG_lexical_block ]
+!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"bar", metadata !"bar", metadata !"bar", metadata !3, i32 8639, metadata !4, i1 true, i1 true, i32 0, i32 0, null} ; [ DW_TAG_subprogram ]
+!3 = metadata !{i32 458769, i32 0, i32 1, metadata !"c-parser.c", metadata !"llvmgcc", metadata !"LLVM build 00", i1 true, i1 false, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
+!4 = metadata !{i32 458773, metadata !3, metadata !"", metadata !3, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !5, i32 0} ; [ DW_TAG_subroutine_type ]
+!5 = metadata !{metadata !6}
+!6 = metadata !{i32 458788, metadata !3, metadata !"char", metadata !3, i32 0, i64 8, i64 8, i64 0, i32 0, i32 6} ; [ DW_TAG_base_type ]
+!7 = metadata !{i32 8648, i32 0, metadata !8, null}
+!8 = metadata !{i32 458763, metadata !9}          ; [ DW_TAG_lexical_block ]
+!9 = metadata !{i32 458763, metadata !10}         ; [ DW_TAG_lexical_block ]
+!10 = metadata !{i32 458798, i32 0, metadata !3, metadata !"bar2", metadata !"bar2", metadata !"bar2", metadata !3, i32 8639, metadata !4, i1 true, i1 true, i32 0, i32 0, null} ; [ DW_TAG_subprogram ]
+!11 = metadata !{i32 8652, i32 0, metadata !1, null}