Index: lib/IR/Metadata.cpp
===================================================================
--- lib/IR/Metadata.cpp
+++ lib/IR/Metadata.cpp
@@ -90,7 +90,11 @@
 }
 
 void MDNodeOperand::allUsesReplacedWith(Value *NV) {
-  getParent()->replaceOperand(this, NV);
+  // Void type operands aren't allowed anyway.
+  if (NV->getType()->isVoidTy())
+    deleted();
+  else
+    getParent()->replaceOperand(this, NV);
 }
 
 //===----------------------------------------------------------------------===//
Index: test/DebugInfo/voidMDNode.ll
===================================================================
--- /dev/null
+++ test/DebugInfo/voidMDNode.ll
@@ -0,0 +1,65 @@
+; RUN: opt -sroa -instcombine < %s | FileCheck %s
+
+; IR generated from (the obvisouly wrong):
+; void foo(void) {}
+; void baz() {
+;	int deadvar = ((int (*)(void))&foo)();
+; }
+
+; Function Attrs: nounwind ssp uwtable
+define void @foo() #0 {
+entry:
+  ret void, !dbg !17
+}
+
+; Function Attrs: nounwind ssp uwtable
+define void @baz() #0 {
+entry:
+  %deadvar = alloca i32, align 4
+; This dbg.declare will be turned in a dbg.value describing the bellow
+; store by sroa. The created dbg.value first argument will be the %call
+; value.
+  call void @llvm.dbg.declare(metadata !{i32* %deadvar}, metadata !18, metadata !19), !dbg !20
+  %call = call i32 bitcast (void ()* @foo to i32 ()*)(), !dbg !21
+; When instcombine removes the bitcast in the call instruction, it will
+; RAUW the %call value with the replacement instruction that is of void
+; type. Check that the dbg.value get's nullified rather that having a
+; bad reference to a void Value.
+;CHECK-NOT: <badref>
+  store i32 %call, i32* %deadvar, align 4, !dbg !21
+  ret void, !dbg !22
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { nounwind ssp 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 }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!14, !15}
+!llvm.ident = !{!16}
+
+!0 = metadata !{metadata !"0x11\0012\00clang version 3.6.0 \000\00\000\00\001", metadata !1, metadata !2, metadata !3, metadata !8, metadata !2, metadata !2} ; [ DW_TAG_compile_unit ] [/tmp/voidmetadata.c] [DW_LANG_C99]
+!1 = metadata !{metadata !"voidmetadata.c", metadata !"/tmp"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{metadata !"0xf\00\000\0064\0064\000\000", null, null, metadata !5} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from ]
+!5 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !6, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!6 = metadata !{metadata !7}
+!7 = 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]
+!8 = metadata !{metadata !9, metadata !13}
+!9 = metadata !{metadata !"0x2e\00foo\00foo\00\002\000\001\000\000\00256\000\002", metadata !1, metadata !10, metadata !11, null, void ()* @foo, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 2] [def] [foo]
+!10 = metadata !{metadata !"0x29", metadata !1}   ; [ DW_TAG_file_type ] [/tmp/voidmetadata.c]
+!11 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !12, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!12 = metadata !{null}
+!13 = metadata !{metadata !"0x2e\00baz\00baz\00\004\000\001\000\000\000\000\004", metadata !1, metadata !10, metadata !11, null, void ()* @baz, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 4] [def] [baz]
+!14 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}
+!15 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
+!16 = metadata !{metadata !"clang version 3.6.0 "}
+!17 = metadata !{i32 2, i32 17, metadata !9, null}
+!18 = metadata !{metadata !"0x100\00deadvar\005\000", metadata !13, metadata !10, metadata !7} ; [ DW_TAG_auto_variable ] [deadvar] [line 5]
+!19 = metadata !{metadata !"0x102"}               ; [ DW_TAG_expression ]
+!20 = metadata !{i32 5, i32 6, metadata !13, null}
+!21 = metadata !{i32 5, i32 16, metadata !13, null}
+!22 = metadata !{i32 6, i32 1, metadata !13, null}