diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index a0d58c6310c..7150a09cd4c 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1144,6 +1144,7 @@ bool DwarfDebug::addCurrentFnArgument(DbgVariable *Var, LexicalScope *Scope) {
   // arguments does the function have at source level.
   if (ArgNo > Size)
     CurrentFnArguments.resize(ArgNo * 2);
+  assert(!CurrentFnArguments[ArgNo - 1]);
   CurrentFnArguments[ArgNo - 1] = Var;
   return true;
 }
@@ -1309,10 +1310,7 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
       continue;
 
     LexicalScope *Scope = nullptr;
-    if (DV.getTag() == dwarf::DW_TAG_arg_variable &&
-        DISubprogram(DV.getContext()).describes(CurFn->getFunction()))
-      Scope = LScopes.getCurrentFunctionScope();
-    else if (MDNode *IA = DV.getInlinedAt()) {
+    if (MDNode *IA = DV.getInlinedAt()) {
       DebugLoc DL = DebugLoc::getFromDILocation(IA);
       Scope = LScopes.findInlinedScope(DebugLoc::get(
           DL.getLine(), DL.getCol(), DV.getContext(), IA));
diff --git a/test/DebugInfo/X86/recursive_inlining.ll b/test/DebugInfo/X86/recursive_inlining.ll
new file mode 100644
index 00000000000..3949ad68475
--- /dev/null
+++ b/test/DebugInfo/X86/recursive_inlining.ll
@@ -0,0 +1,275 @@
+; REQUIRES: object-emission
+
+; RUN: llc -filetype=obj -O0 < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; This isn't a very pretty test case - I imagine there might be other ways to
+; tickle the optimizers into producing the desired code, but I haven't found
+; them.
+
+; The issue is when a function is inlined into itself, the inlined argument
+; accidentally overwrote the concrete argument and was lost.
+
+; IR generated from the following source compiled with clang -g:
+; void fn1(void *);
+; void fn2(int, int, int, int);
+; void fn3();
+; void fn8();
+; struct C {
+;   int b;
+;   void m_fn2() {
+;     fn8();
+;     if (b) fn2(0, 0, 0, 0);
+;     fn3();
+;   }
+; };
+; C *x;
+; inline void fn7() {}
+; void fn6() {
+;   fn8();
+;   x->m_fn2();
+;   fn7();
+; }
+; void fn3() { fn6(); }
+; void fn4() { x->m_fn2(); }
+; void fn5() { x->m_fn2(); }
+
+; The definition of C and declaration of C::m_fn2
+; CHECK: DW_TAG_structure_type
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK: DW_TAG_member
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK: [[M_FN2_DECL:.*]]:   DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_name {{.*}} "m_fn2"
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK: [[M_FN2_THIS_DECL:.*]]:     DW_TAG_formal_parameter
+
+; The abstract definition of C::m_fn2
+; CHECK: [[M_FN2_ABS_DEF:.*]]: DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK:   DW_AT_specification {{.*}} {[[M_FN2_DECL]]}
+; CHECK-NOT: DW_TAG
+; CHECK:   DW_AT_inline
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK: [[M_FN2_THIS_ABS_DEF:.*]]:   DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_name {{.*}} "this"
+
+; Skip some other functions
+; CHECK: DW_TAG_subprogram
+; CHECK: DW_TAG_subprogram
+; CHECK: DW_TAG_subprogram
+
+; The concrete definition of C::m_fn2
+; CHECK: DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK:   DW_AT_abstract_origin {{.*}} {[[M_FN2_ABS_DEF]]}
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:   DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_abstract_origin {{.*}} {[[M_FN2_THIS_ABS_DEF]]}
+; CHECK-NOT: {{DW_TAG|NULL}}
+; Inlined fn3:
+; CHECK:     DW_TAG_inlined_subroutine
+; CHECK-NOT: {{DW_TAG|NULL}}
+; Inlined fn6:
+; CHECK:       DW_TAG_inlined_subroutine
+; CHECK-NOT: {{DW_TAG|NULL}}
+; Inlined C::m_fn2:
+; CHECK:         DW_TAG_inlined_subroutine
+; CHECK-NOT: DW_TAG
+; CHECK:           DW_AT_abstract_origin {{.*}} {[[M_FN2_ABS_DEF]]}
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:           DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:              DW_AT_abstract_origin {{.*}} {[[M_FN2_THIS_ABS_DEF]]}
+
+
+
+%struct.C = type { i32 }
+
+@x = global %struct.C* null, align 8
+
+; Function Attrs: nounwind
+define void @_Z3fn6v() #0 {
+entry:
+  tail call void @_Z3fn8v() #3, !dbg !31
+  %0 = load %struct.C** @x, align 8, !dbg !32, !tbaa !33
+  tail call void @llvm.dbg.value(metadata !{%struct.C* %0}, i64 0, metadata !37) #3, !dbg !38
+  tail call void @_Z3fn8v() #3, !dbg !39
+  %b.i = getelementptr inbounds %struct.C* %0, i64 0, i32 0, !dbg !40
+  %1 = load i32* %b.i, align 4, !dbg !40, !tbaa !42
+  %tobool.i = icmp eq i32 %1, 0, !dbg !40
+  br i1 %tobool.i, label %_ZN1C5m_fn2Ev.exit, label %if.then.i, !dbg !40
+
+if.then.i:                                        ; preds = %entry
+  tail call void @_Z3fn2iiii(i32 0, i32 0, i32 0, i32 0) #3, !dbg !45
+  br label %_ZN1C5m_fn2Ev.exit, !dbg !45
+
+_ZN1C5m_fn2Ev.exit:                               ; preds = %entry, %if.then.i
+  tail call void @_Z3fn3v() #3, !dbg !47
+  ret void, !dbg !48
+}
+
+declare void @_Z3fn8v() #1
+
+; Function Attrs: nounwind
+define linkonce_odr void @_ZN1C5m_fn2Ev(%struct.C* nocapture readonly %this) #0 align 2 {
+entry:
+  tail call void @llvm.dbg.value(metadata !{%struct.C* %this}, i64 0, metadata !24), !dbg !49
+  tail call void @_Z3fn8v() #3, !dbg !50
+  %b = getelementptr inbounds %struct.C* %this, i64 0, i32 0, !dbg !51
+  %0 = load i32* %b, align 4, !dbg !51, !tbaa !42
+  %tobool = icmp eq i32 %0, 0, !dbg !51
+  br i1 %tobool, label %if.end, label %if.then, !dbg !51
+
+if.then:                                          ; preds = %entry
+  tail call void @_Z3fn2iiii(i32 0, i32 0, i32 0, i32 0) #3, !dbg !52
+  br label %if.end, !dbg !52
+
+if.end:                                           ; preds = %entry, %if.then
+  tail call void @_Z3fn8v() #3, !dbg !53
+  %1 = load %struct.C** @x, align 8, !dbg !56, !tbaa !33
+  tail call void @llvm.dbg.value(metadata !{%struct.C* %1}, i64 0, metadata !57) #3, !dbg !58
+  tail call void @_Z3fn8v() #3, !dbg !59
+  %b.i.i = getelementptr inbounds %struct.C* %1, i64 0, i32 0, !dbg !60
+  %2 = load i32* %b.i.i, align 4, !dbg !60, !tbaa !42
+  %tobool.i.i = icmp eq i32 %2, 0, !dbg !60
+  br i1 %tobool.i.i, label %_Z3fn6v.exit, label %if.then.i.i, !dbg !60
+
+if.then.i.i:                                      ; preds = %if.end
+  tail call void @_Z3fn2iiii(i32 0, i32 0, i32 0, i32 0) #3, !dbg !61
+  br label %_Z3fn6v.exit, !dbg !61
+
+_Z3fn6v.exit:                                     ; preds = %if.end, %if.then.i.i
+  tail call void @_Z3fn3v() #3, !dbg !62
+  ret void, !dbg !63
+}
+
+; Function Attrs: nounwind
+define void @_Z3fn3v() #0 {
+entry:
+  br label %tailrecurse
+
+tailrecurse:                                      ; preds = %tailrecurse.backedge, %entry
+  tail call void @_Z3fn8v() #3, !dbg !64
+  %0 = load %struct.C** @x, align 8, !dbg !66, !tbaa !33
+  tail call void @llvm.dbg.value(metadata !{%struct.C* %0}, i64 0, metadata !67) #3, !dbg !68
+  tail call void @_Z3fn8v() #3, !dbg !69
+  %b.i.i = getelementptr inbounds %struct.C* %0, i64 0, i32 0, !dbg !70
+  %1 = load i32* %b.i.i, align 4, !dbg !70, !tbaa !42
+  %tobool.i.i = icmp eq i32 %1, 0, !dbg !70
+  br i1 %tobool.i.i, label %tailrecurse.backedge, label %if.then.i.i, !dbg !70
+
+tailrecurse.backedge:                             ; preds = %tailrecurse, %if.then.i.i
+  br label %tailrecurse
+
+if.then.i.i:                                      ; preds = %tailrecurse
+  tail call void @_Z3fn2iiii(i32 0, i32 0, i32 0, i32 0) #3, !dbg !71
+  br label %tailrecurse.backedge, !dbg !71
+}
+
+; Function Attrs: nounwind
+define void @_Z3fn4v() #0 {
+entry:
+  %0 = load %struct.C** @x, align 8, !dbg !72, !tbaa !33
+  tail call void @_ZN1C5m_fn2Ev(%struct.C* %0), !dbg !72
+  ret void, !dbg !72
+}
+
+; Function Attrs: nounwind
+define void @_Z3fn5v() #0 {
+entry:
+  %0 = load %struct.C** @x, align 8, !dbg !73, !tbaa !33
+  tail call void @_ZN1C5m_fn2Ev(%struct.C* %0), !dbg !73
+  ret void, !dbg !73
+}
+
+declare void @_Z3fn2iiii(i32, i32, i32, i32) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata) #2
+
+attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-realign-stack" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-realign-stack" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!28, !29}
+!llvm.ident = !{!30}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.6.0 ", i1 true, metadata !"", i32 0, metadata !2, metadata !3, metadata !13, metadata !26, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/usr/local/google/home/blaikie/dev/scratch/missing_concrete_variable_on_darwin/reduce/<stdin>] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"<stdin>", metadata !"/usr/local/google/home/blaikie/dev/scratch/missing_concrete_variable_on_darwin/reduce"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786451, metadata !5, null, metadata !"C", i32 5, i64 32, i64 32, i32 0, i32 0, null, metadata !6, i32 0, null, null, metadata !"_ZTS1C"} ; [ DW_TAG_structure_type ] [C] [line 5, size 32, align 32, offset 0] [def] [from ]
+!5 = metadata !{metadata !"recursive_inlining.cpp", metadata !"/usr/local/google/home/blaikie/dev/scratch/missing_concrete_variable_on_darwin/reduce"}
+!6 = metadata !{metadata !7, metadata !9}
+!7 = metadata !{i32 786445, metadata !5, metadata !"_ZTS1C", metadata !"b", i32 6, i64 32, i64 32, i64 0, i32 0, metadata !8} ; [ DW_TAG_member ] [b] [line 6, size 32, align 32, offset 0] [from int]
+!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = metadata !{i32 786478, metadata !5, metadata !"_ZTS1C", metadata !"m_fn2", metadata !"m_fn2", metadata !"_ZN1C5m_fn2Ev", i32 7, metadata !10, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 true, null, null, i32 0, null, i32 7} ; [ DW_TAG_subprogram ] [line 7] [m_fn2]
+!10 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !11, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!11 = metadata !{null, metadata !12}
+!12 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 1088, metadata !"_ZTS1C"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from _ZTS1C]
+!13 = metadata !{metadata !14, metadata !18, metadata !19, metadata !20, metadata !21, metadata !22}
+!14 = metadata !{i32 786478, metadata !5, metadata !15, metadata !"fn6", metadata !"fn6", metadata !"_Z3fn6v", i32 15, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void ()* @_Z3fn6v, null, null, metadata !2, i32 15} ; [ DW_TAG_subprogram ] [line 15] [def] [fn6]
+!15 = metadata !{i32 786473, metadata !5}         ; [ DW_TAG_file_type ] [/usr/local/google/home/blaikie/dev/scratch/missing_concrete_variable_on_darwin/reduce/recursive_inlining.cpp]
+!16 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !17, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!17 = metadata !{null}
+!18 = metadata !{i32 786478, metadata !5, metadata !15, metadata !"fn3", metadata !"fn3", metadata !"_Z3fn3v", i32 20, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void ()* @_Z3fn3v, null, null, metadata !2, i32 20} ; [ DW_TAG_subprogram ] [line 20] [def] [fn3]
+!19 = metadata !{i32 786478, metadata !5, metadata !15, metadata !"fn4", metadata !"fn4", metadata !"_Z3fn4v", i32 21, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void ()* @_Z3fn4v, null, null, metadata !2, i32 21} ; [ DW_TAG_subprogram ] [line 21] [def] [fn4]
+!20 = metadata !{i32 786478, metadata !5, metadata !15, metadata !"fn5", metadata !"fn5", metadata !"_Z3fn5v", i32 22, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void ()* @_Z3fn5v, null, null, metadata !2, i32 22} ; [ DW_TAG_subprogram ] [line 22] [def] [fn5]
+!21 = metadata !{i32 786478, metadata !5, metadata !15, metadata !"fn7", metadata !"fn7", metadata !"_Z3fn7v", i32 14, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, null, null, null, metadata !2, i32 14} ; [ DW_TAG_subprogram ] [line 14] [def] [fn7]
+!22 = metadata !{i32 786478, metadata !5, metadata !"_ZTS1C", metadata !"m_fn2", metadata !"m_fn2", metadata !"_ZN1C5m_fn2Ev", i32 7, metadata !10, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void (%struct.C*)* @_ZN1C5m_fn2Ev, null, metadata !9, metadata !23, i32 7} ; [ DW_TAG_subprogram ] [line 7] [def] [m_fn2]
+!23 = metadata !{metadata !24}
+!24 = metadata !{i32 786689, metadata !22, metadata !"this", null, i32 16777216, metadata !25, i32 1088, i32 0} ; [ DW_TAG_arg_variable ] [this] [line 0]
+!25 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !"_ZTS1C"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from _ZTS1C]
+!26 = metadata !{metadata !27}
+!27 = metadata !{i32 786484, i32 0, null, metadata !"x", metadata !"x", metadata !"", metadata !15, i32 13, metadata !25, i32 0, i32 1, %struct.C** @x, null} ; [ DW_TAG_variable ] [x] [line 13] [def]
+!28 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!29 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
+!30 = metadata !{metadata !"clang version 3.6.0 "}
+!31 = metadata !{i32 16, i32 0, metadata !14, null}
+!32 = metadata !{i32 17, i32 0, metadata !14, null}
+!33 = metadata !{metadata !34, metadata !34, i64 0}
+!34 = metadata !{metadata !"any pointer", metadata !35, i64 0}
+!35 = metadata !{metadata !"omnipotent char", metadata !36, i64 0}
+!36 = metadata !{metadata !"Simple C/C++ TBAA"}
+!37 = metadata !{i32 786689, metadata !22, metadata !"this", null, i32 16777216, metadata !25, i32 1088, metadata !32} ; [ DW_TAG_arg_variable ] [this] [line 0]
+!38 = metadata !{i32 0, i32 0, metadata !22, metadata !32}
+!39 = metadata !{i32 8, i32 0, metadata !22, metadata !32} ; [ DW_TAG_imported_declaration ]
+!40 = metadata !{i32 9, i32 0, metadata !41, metadata !32}
+!41 = metadata !{i32 786443, metadata !5, metadata !22, i32 9, i32 0, i32 0, i32 0} ; [ DW_TAG_lexical_block ] [/usr/local/google/home/blaikie/dev/scratch/missing_concrete_variable_on_darwin/reduce/recursive_inlining.cpp]
+!42 = metadata !{metadata !43, metadata !44, i64 0}
+!43 = metadata !{metadata !"_ZTS1C", metadata !44, i64 0}
+!44 = metadata !{metadata !"int", metadata !35, i64 0}
+!45 = metadata !{i32 9, i32 0, metadata !46, metadata !32}
+!46 = metadata !{i32 786443, metadata !5, metadata !41, i32 9, i32 0, i32 1, i32 1} ; [ DW_TAG_lexical_block ] [/usr/local/google/home/blaikie/dev/scratch/missing_concrete_variable_on_darwin/reduce/recursive_inlining.cpp]
+!47 = metadata !{i32 10, i32 0, metadata !22, metadata !32}
+!48 = metadata !{i32 19, i32 0, metadata !14, null}
+!49 = metadata !{i32 0, i32 0, metadata !22, null}
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+!52 = metadata !{i32 9, i32 0, metadata !46, null}
+!53 = metadata !{i32 16, i32 0, metadata !14, metadata !54}
+!54 = metadata !{i32 20, i32 0, metadata !18, metadata !55}
+!55 = metadata !{i32 10, i32 0, metadata !22, null}
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