Index: llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
@@ -31,7 +31,7 @@
   assert(MI.isDebugValue());
   assert(MI.getNumOperands() == 4);
   // If location of variable is described using a register (directly or
-  // indirecltly), this register is always a first operand.
+  // indirectly), this register is always a first operand.
   return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
 }
 
@@ -164,7 +164,9 @@
       // Look for register defs and register masks. Register masks are
       // typically on calls and they clobber everything not in the mask.
       for (const MachineOperand &MO : MI.operands()) {
-        if (MO.isReg() && MO.isDef() && MO.getReg()) {
+        // Skip virtual registers since they are handled by the parent.
+        if (MO.isReg() && MO.isDef() && MO.getReg() &&
+            !TRI->isVirtualRegister(MO.getReg())) {
           for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
                ++AI)
             Regs.set(*AI);
@@ -192,12 +194,18 @@
         // some variables.
         for (const MachineOperand &MO : MI.operands()) {
           if (MO.isReg() && MO.isDef() && MO.getReg()) {
+            // If this is a virtual register, only clobber it since it doesn't
+            // have aliases.
+            if (TRI->isVirtualRegister(MO.getReg()))
+              clobberRegisterUses(RegVars, MO.getReg(), Result, MI);
             // If this is a register def operand, it may end a debug value
             // range.
-            for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
-                 ++AI)
-              if (ChangingRegs.test(*AI))
-                clobberRegisterUses(RegVars, *AI, Result, MI);
+            else {
+              for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
+                   ++AI)
+                if (ChangingRegs.test(*AI))
+                  clobberRegisterUses(RegVars, *AI, Result, MI);
+            }
           } else if (MO.isRegMask()) {
             // If this is a register mask operand, clobber all debug values in
             // non-CSRs.
@@ -238,7 +246,8 @@
     if (!MBB.empty() && &MBB != &MF->back()) {
       for (auto I = RegVars.begin(), E = RegVars.end(); I != E;) {
         auto CurElem = I++; // CurElem can be erased below.
-        if (ChangingRegs.test(CurElem->first))
+        if (TRI->isVirtualRegister(CurElem->first) ||
+            ChangingRegs.test(CurElem->first))
           clobberRegisterUses(RegVars, CurElem, Result, MBB.back());
       }
     }
Index: llvm/trunk/test/CodeGen/WebAssembly/dbgvalue.ll
===================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/dbgvalue.ll
+++ llvm/trunk/test/CodeGen/WebAssembly/dbgvalue.ll
@@ -0,0 +1,69 @@
+; RUN: llc < %s -O0 -verify-machineinstrs -mtriple=wasm32-unknown-unknown | FileCheck %s
+; CHECK: BB#0
+; CHECK: #DEBUG_VALUE: usage:self <- %vreg4
+; CHECK: BB#1
+; CHECK: DW_TAG_variable
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+%0 = type opaque
+
+@key = external local_unnamed_addr global [15 x i8], align 1
+@.str = external unnamed_addr constant [33 x i8], align 1
+
+; Function Attrs: nounwind
+define internal i32 @0(i8*) local_unnamed_addr !dbg !14 !type !22 {
+  tail call void @llvm.dbg.value(metadata i8* %0, i64 0, metadata !21, metadata !23), !dbg !24
+  %2 = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([33 x i8], [33 x i8]* @.str, i32 0, i32 0), i8* %0), !dbg !25
+  br i1 1, label %a, label %b
+a:
+  %3 = add i32 %2, %2
+  br label %c
+
+b:
+  %4 = sub i32 %2, %2
+  br label %c
+
+c:
+  %5 = phi i32 [ %3, %a ], [ %4, %b ]
+  %6 = add i32 ptrtoint (i32 (i8*)* @0 to i32), %5
+  ret i32 %6, !dbg !26
+}
+
+; Function Attrs: nounwind
+declare i32 @printf(i8* nocapture readonly, ...) local_unnamed_addr
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!11, !12}
+!llvm.ident = !{!13}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 (trunk 273884) (llvm/trunk 273897)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3)
+!1 = !DIFile(filename: "crash.c", directory: "wasm/tests")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DIGlobalVariable(name: "key", scope: !0, file: !1, line: 7, type: !5, isLocal: false, isDefinition: true, variable: [15 x i8]* @key)
+!5 = !DICompositeType(tag: DW_TAG_array_type, baseType: !6, size: 120, align: 8, elements: !9)
+!6 = !DIDerivedType(tag: DW_TAG_typedef, name: "uint8_t", file: !7, line: 185, baseType: !8)
+!7 = !DIFile(filename: "wasm/emscripten/system/include/libc/bits/alltypes.h", directory: "wasm/tests")
+!8 = !DIBasicType(name: "unsigned char", size: 8, align: 8, encoding: DW_ATE_unsigned_char)
+!9 = !{!10}
+!10 = !DISubrange(count: 15)
+!11 = !{i32 2, !"Dwarf Version", i32 4}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+!13 = !{!"clang version 3.9.0 (trunk 273884) (llvm/trunk 273897)"}
+!14 = distinct !DISubprogram(name: "usage", scope: !1, file: !1, line: 15, type: !15, isLocal: false, isDefinition: true, scopeLine: 15, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !20)
+!15 = !DISubroutineType(types: !16)
+!16 = !{!17, !18}
+!17 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 32, align: 32)
+!19 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!20 = !{!21}
+!21 = !DILocalVariable(name: "self", arg: 1, scope: !14, file: !1, line: 15, type: !18)
+!22 = !{i64 0, !"_ZTSFiPcE"}
+!23 = !DIExpression()
+!24 = !DILocation(line: 15, column: 17, scope: !14)
+!25 = !DILocation(line: 16, column: 3, scope: !14)
+!26 = !DILocation(line: 17, column: 3, scope: !14)