diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 4dd36830a44..70f0238d513 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1254,11 +1254,12 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
     assert(DV.isVariable());
     if (!Processed.insert(DV))
       continue;
-    if (LexicalScope *Scope = LScopes.findLexicalScope(DV.getContext()))
-      addScopeVariable(
-          Scope,
-          new DbgVariable(DV, findAbstractVariable(DV, Scope->getScopeNode()),
-                          this));
+    if (LexicalScope *Scope = LScopes.findLexicalScope(DV.getContext())) {
+      auto *RegVar = new DbgVariable(
+          DV, findAbstractVariable(DV, Scope->getScopeNode()), this);
+      if (!addCurrentFnArgument(RegVar, Scope))
+        addScopeVariable(Scope, RegVar);
+    }
   }
 }
 
diff --git a/test/DebugInfo/dead-argument-order.ll b/test/DebugInfo/dead-argument-order.ll
new file mode 100644
index 00000000000..921a9730901
--- /dev/null
+++ b/test/DebugInfo/dead-argument-order.ll
@@ -0,0 +1,80 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; Built from the following source with clang -O1
+; struct S { int i; };
+; int function(struct S s, int i) { return s.i + i; }
+
+; Due to the X86_64 ABI, 's' is passed in registers and once optimized, the
+; entirety of 's' is never reconstituted, since only the int is required, and
+; thus the variable's location is unknown/dead to debug info.
+
+; Future/current work should enable us to describe partial variables, which, in
+; this case, happens to be the entire variable.
+
+; CHECK: DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK:   DW_AT_name {{.*}} "function"
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:   DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_name {{.*}} "s"
+; CHECK-NOT: DW_TAG
+; FIXME: Even though 's' is never reconstituted into a struct, the one member
+; variable is still live and used, and so we should be able to describe 's's
+; location as the location of that int.
+; CHECK-NOT: DW_AT_location
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:   DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_name {{.*}} "i"
+; CHECK:     DW_AT_location
+
+
+%struct.S = type { i32 }
+
+; Function Attrs: nounwind readnone uwtable
+define i32 @_Z8function1Si(i32 %s.coerce, i32 %i) #0 {
+entry:
+  tail call void @llvm.dbg.declare(metadata !19, metadata !14), !dbg !20
+  tail call void @llvm.dbg.value(metadata !{i32 %i}, i64 0, metadata !15), !dbg !20
+  %add = add nsw i32 %i, %s.coerce, !dbg !20
+  ret i32 %add, !dbg !20
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata) #1
+
+attributes #0 = { nounwind readnone uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!16, !17}
+!llvm.ident = !{!18}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 ", i1 true, metadata !"", i32 0, metadata !2, metadata !3, metadata !8, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/dead-argument-order.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"dead-argument-order.cpp", metadata !"/tmp/dbginfo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786451, metadata !1, null, metadata !"S", i32 1, i64 32, i64 32, i32 0, i32 0, null, metadata !5, i32 0, null, null, metadata !"_ZTS1S"} ; [ DW_TAG_structure_type ] [S] [line 1, size 32, align 32, offset 0] [def] [from ]
+!5 = metadata !{metadata !6}
+!6 = metadata !{i32 786445, metadata !1, metadata !"_ZTS1S", metadata !"i", i32 1, i64 32, i64 32, i64 0, i32 0, metadata !7} ; [ DW_TAG_member ] [i] [line 1, size 32, align 32, offset 0] [from int]
+!7 = 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]
+!8 = metadata !{metadata !9}
+!9 = metadata !{i32 786478, metadata !1, metadata !10, metadata !"function", metadata !"function", metadata !"_Z8function1Si", i32 2, metadata !11, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, i32 (i32, i32)* @_Z8function1Si, null, null, metadata !13, i32 2} ; [ DW_TAG_subprogram ] [line 2] [def] [function]
+!10 = metadata !{i32 786473, metadata !1}         ; [ DW_TAG_file_type ] [/tmp/dbginfo/dead-argument-order.cpp]
+!11 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !12, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!12 = metadata !{metadata !7, metadata !4, metadata !7}
+!13 = metadata !{metadata !14, metadata !15}
+!14 = metadata !{i32 786689, metadata !9, metadata !"s", metadata !10, i32 16777218, metadata !"_ZTS1S", i32 0, i32 0} ; [ DW_TAG_arg_variable ] [s] [line 2]
+!15 = metadata !{i32 786689, metadata !9, metadata !"i", metadata !10, i32 33554434, metadata !7, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [i] [line 2]
+!16 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!17 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
+!18 = metadata !{metadata !"clang version 3.5.0 "}
+!19 = metadata !{%struct.S* undef}
+!20 = metadata !{i32 2, i32 0, metadata !9, null}
+