Index: lld/trunk/wasm/Symbols.h
===================================================================
--- lld/trunk/wasm/Symbols.h
+++ lld/trunk/wasm/Symbols.h
@@ -23,6 +23,8 @@
 class InputFile;
 class InputChunk;
 
+#define INVALID_INDEX UINT32_MAX
+
 // The base class for real symbol classes.
 class Symbol {
 public:
@@ -82,7 +84,7 @@
   uint32_t Flags;
   InputFile *File;
   InputChunk *Chunk;
-  llvm::Optional<uint32_t> OutputIndex;
+  uint32_t OutputIndex = INVALID_INDEX;
 };
 
 class FunctionSymbol : public Symbol {
@@ -110,7 +112,7 @@
                  InputChunk *C)
       : Symbol(Name, K, Flags, F, C) {}
 
-  llvm::Optional<uint32_t> TableIndex;
+  uint32_t TableIndex = INVALID_INDEX;
 
   // Explict function type, needed for undefined or synthetic functions only.
   const WasmSignature *FunctionType = nullptr;
@@ -237,6 +239,8 @@
 
 template <typename T, typename... ArgT>
 T *replaceSymbol(Symbol *S, ArgT &&... Arg) {
+  static_assert(std::is_trivially_destructible<T>(),
+                "Symbol types must be trivially destructible");
   static_assert(sizeof(T) <= sizeof(SymbolUnion), "Symbol too small");
   static_assert(alignof(T) <= alignof(SymbolUnion),
                 "SymbolUnion not aligned enough");
Index: lld/trunk/wasm/Symbols.cpp
===================================================================
--- lld/trunk/wasm/Symbols.cpp
+++ lld/trunk/wasm/Symbols.cpp
@@ -31,19 +31,20 @@
 bool Symbol::hasOutputIndex() const {
   if (auto *F = dyn_cast_or_null<InputFunction>(Chunk))
     return F->hasOutputIndex();
-  return OutputIndex.hasValue();
+  return OutputIndex != INVALID_INDEX;
 }
 
 uint32_t Symbol::getOutputIndex() const {
   if (auto *F = dyn_cast_or_null<InputFunction>(Chunk))
     return F->getOutputIndex();
-  return OutputIndex.getValue();
+  assert(OutputIndex != INVALID_INDEX);
+  return OutputIndex;
 }
 
 void Symbol::setOutputIndex(uint32_t Index) {
   DEBUG(dbgs() << "setOutputIndex " << Name << " -> " << Index << "\n");
   assert(!dyn_cast_or_null<InputFunction>(Chunk));
-  assert(!OutputIndex.hasValue());
+  assert(OutputIndex == INVALID_INDEX);
   OutputIndex = Index;
 }
 
@@ -85,13 +86,14 @@
 uint32_t FunctionSymbol::getTableIndex() const {
   if (auto *F = dyn_cast_or_null<InputFunction>(Chunk))
     return F->getTableIndex();
-  return TableIndex.getValue();
+  assert(TableIndex != INVALID_INDEX);
+  return TableIndex;
 }
 
 bool FunctionSymbol::hasTableIndex() const {
   if (auto *F = dyn_cast_or_null<InputFunction>(Chunk))
     return F->hasTableIndex();
-  return TableIndex.hasValue();
+  return TableIndex != INVALID_INDEX;
 }
 
 void FunctionSymbol::setTableIndex(uint32_t Index) {
@@ -103,7 +105,7 @@
     return;
   }
   DEBUG(dbgs() << "setTableIndex " << Name << " -> " << Index << "\n");
-  assert(!TableIndex.hasValue());
+  assert(TableIndex == INVALID_INDEX);
   TableIndex = Index;
 }