diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 3d49db3db7e7..c1c50df9ad34 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -177,7 +177,12 @@ void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
       // A later indexed parameter has been found, insert immediately before it.
       if (CurNum > ArgNum)
         break;
-      assert(CurNum != ArgNum);
+      // FIXME: There are still some cases where two inlined functions are
+      // conflated together (two calls to the same function at the same
+      // location (eg: via a macro, or without column info, etc)) and then
+      // their arguments are conflated as well.
+      assert((LS->getParent() || CurNum != ArgNum) &&
+             "Missing parameter for top level (non-inlined) function");
       ++I;
     }
     Vars.insert(I, Var);
diff --git a/llvm/test/DebugInfo/duplicate_inline.ll b/llvm/test/DebugInfo/duplicate_inline.ll
new file mode 100644
index 000000000000..008b52f7ba75
--- /dev/null
+++ b/llvm/test/DebugInfo/duplicate_inline.ll
@@ -0,0 +1,117 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf < %s -filetype=obj | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; Built with clang from the following source:
+; void f1(int);
+; __attribute__((always_inline)) inline void f2(int i) { f1(i); }
+;
+; #define MULTICALL \
+;   f2(x);          \
+;   f2(y);
+;
+; void f3(int x, int y) { MULTICALL; }
+
+; FIXME: This produces only one inlined_subroutine, with two formal_parameters
+; (both named "this"), one for each of the actual inlined subroutines.  ;
+; Inlined scopes are differentiated by the combination of 'inlined at' (call)
+; location and the location within the function. If two calls to the same
+; function occur at the same location the scopes end up conflated and there
+; appears to be only one inlined function.
+; To fix this, we'd need to add some kind of unique metadata per call site, possibly something like:
+;
+; !42 = metadata !{i32 1, i32 0, metadata !43, metadata !44}
+; !44 = metadata !{i32 2, i32 0, metadata !45, null}
+;
+; ->
+;
+; !42 = metadata !{i32 1, i32 0, metadata !43, metadata !44}
+; !44 = metadata !{metadata !45, metadata !44}
+; !45 = metadata !{i32 2, i32 0, metadata !45, null}
+;
+; since cycles in metadata are not uniqued, the !44 node would not be shared
+; between calls to the same function from the same location, ensuring separate
+; inlined subroutines would be generated.
+;
+; Once this is done, the (insufficient) hack in clang that adds column
+; information to call sites to differentiate inlined callers can be removed as it
+; will no longer be necessary.
+;
+; While it might be nice to omit the duplicate parameter in this case (while
+; we wait/work on the real fix), it's actually better to leave it in because it
+; allows us to hold the invariant that every DbgVariable has a DIE, every time.
+; This has proved valuable in finding other bugs, so I want to avoid removing the
+; invariant/assertion. Besides, we don't know which one's the right one anyway...
+
+; CHECK: DW_TAG_subprogram
+; CHECK:   DW_TAG_inlined_subroutine
+; CHECK:     DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     NULL
+; CHECK-NOT: DW_TAG
+; CHECK:   NULL
+
+; Function Attrs: uwtable
+define void @_Z2f3ii(i32 %x, i32 %y) #0 {
+entry:
+  %i.addr.i1 = alloca i32, align 4
+  %i.addr.i = alloca i32, align 4
+  %x.addr = alloca i32, align 4
+  %y.addr = alloca i32, align 4
+  store i32 %x, i32* %x.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %x.addr}, metadata !15, metadata !16), !dbg !17
+  store i32 %y, i32* %y.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %y.addr}, metadata !18, metadata !16), !dbg !19
+  %0 = load i32* %x.addr, align 4, !dbg !20
+  store i32 %0, i32* %i.addr.i, align 4, !dbg !20
+  call void @llvm.dbg.declare(metadata !{i32* %i.addr.i}, metadata !21, metadata !16), !dbg !22
+  %1 = load i32* %i.addr.i, align 4, !dbg !23
+  call void @_Z2f1i(i32 %1), !dbg !23
+  %2 = load i32* %y.addr, align 4, !dbg !20
+  store i32 %2, i32* %i.addr.i1, align 4, !dbg !20
+  call void @llvm.dbg.declare(metadata !{i32* %i.addr.i1}, metadata !21, metadata !16), !dbg !22
+  %3 = load i32* %i.addr.i1, align 4, !dbg !23
+  call void @_Z2f1i(i32 %3), !dbg !23
+  ret void, !dbg !24
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+declare void @_Z2f1i(i32) #2
+
+attributes #0 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "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 }
+attributes #2 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!12, !13}
+!llvm.ident = !{!14}
+
+!0 = metadata !{metadata !"0x11\004\00clang version 3.6.0 \000\00\000\00\001", metadata !1, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/duplicate_inline.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"duplicate_inline.cpp", metadata !"/tmp/dbginfo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4, metadata !9}
+!4 = metadata !{metadata !"0x2e\00f3\00f3\00_Z2f3ii\008\000\001\000\000\00256\000\008", metadata !1, metadata !5, metadata !6, null, void (i32, i32)* @_Z2f3ii, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 8] [def] [f3]
+!5 = metadata !{metadata !"0x29", metadata !1}    ; [ DW_TAG_file_type ] [/tmp/dbginfo/duplicate_inline.cpp]
+!6 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{null, metadata !8, metadata !8}
+!8 = metadata !{metadata !"0x24\00int\000\0032\0032\000\000\005", null, null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = metadata !{metadata !"0x2e\00f2\00f2\00_Z2f2i\002\000\001\000\000\00256\000\002", metadata !1, metadata !5, metadata !10, null, null, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 2] [def] [f2]
+!10 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !11, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!11 = metadata !{null, metadata !8}
+!12 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!13 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
+!14 = metadata !{metadata !"clang version 3.6.0 "}
+!15 = metadata !{metadata !"0x101\00x\0016777224\000", metadata !4, metadata !5, metadata !8} ; [ DW_TAG_arg_variable ] [x] [line 8]
+!16 = metadata !{metadata !"0x102"}               ; [ DW_TAG_expression ]
+!17 = metadata !{i32 8, i32 13, metadata !4, null}
+!18 = metadata !{metadata !"0x101\00y\0033554440\000", metadata !4, metadata !5, metadata !8} ; [ DW_TAG_arg_variable ] [y] [line 8]
+!19 = metadata !{i32 8, i32 20, metadata !4, null}
+!20 = metadata !{i32 8, i32 25, metadata !4, null}
+!21 = metadata !{metadata !"0x101\00i\0016777218\000", metadata !9, metadata !5, metadata !8} ; [ DW_TAG_arg_variable ] [i] [line 2]
+!22 = metadata !{i32 2, i32 51, metadata !9, metadata !20}
+!23 = metadata !{i32 2, i32 56, metadata !9, metadata !20}
+!24 = metadata !{i32 8, i32 36, metadata !4, null}