Index: wasm/Writer.cpp
===================================================================
--- wasm/Writer.cpp
+++ wasm/Writer.cpp
@@ -40,29 +40,6 @@
 
 namespace {
 
-// Traits for using WasmSignature in a DenseMap.
-struct WasmSignatureDenseMapInfo {
-  static WasmSignature getEmptyKey() {
-    WasmSignature Sig;
-    Sig.ReturnType = 1;
-    return Sig;
-  }
-  static WasmSignature getTombstoneKey() {
-    WasmSignature Sig;
-    Sig.ReturnType = 2;
-    return Sig;
-  }
-  static unsigned getHashValue(const WasmSignature &Sig) {
-    unsigned H = hash_value(Sig.ReturnType);
-    for (int32_t Param : Sig.ParamTypes)
-      H = hash_combine(H, Param);
-    return H;
-  }
-  static bool isEqual(const WasmSignature &LHS, const WasmSignature &RHS) {
-    return LHS == RHS;
-  }
-};
-
 // An init entry to be written to either the synthetic init func or the
 // linking metadata.
 struct WasmInitEntry {
@@ -119,7 +96,7 @@
   uint32_t NumMemoryPages = 0;
 
   std::vector<const WasmSignature *> Types;
-  DenseMap<WasmSignature, int32_t, WasmSignatureDenseMapInfo> TypeIndices;
+  DenseMap<WasmSignature, int32_t> TypeIndices;
   std::vector<const Symbol *> ImportedSymbols;
   unsigned NumImportedFunctions = 0;
   unsigned NumImportedGlobals = 0;
Index: wasm/WriterUtils.h
===================================================================
--- wasm/WriterUtils.h
+++ wasm/WriterUtils.h
@@ -11,13 +11,16 @@
 #define LLD_WASM_WRITERUTILS_H
 
 #include "lld/Common/LLVM.h"
+#include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Object/Wasm.h"
 #include "llvm/Support/raw_ostream.h"
 
 using llvm::raw_ostream;
 
-// Needed for WasmSignatureDenseMapInfo
+namespace llvm {
+
+// Needed for DenseMapInfo<wasm::WasmSignature>
 inline bool operator==(const llvm::wasm::WasmSignature &LHS,
                        const llvm::wasm::WasmSignature &RHS) {
   return LHS.ReturnType == RHS.ReturnType && LHS.ParamTypes == RHS.ParamTypes;
@@ -39,6 +42,32 @@
   return !(LHS == RHS);
 }
 
+// Traits for using WasmSignature in a DenseMap.
+template<> struct DenseMapInfo<wasm::WasmSignature> {
+  static wasm::WasmSignature getEmptyKey() {
+    wasm::WasmSignature Sig;
+    Sig.ReturnType = 1;
+    return Sig;
+  }
+  static wasm::WasmSignature getTombstoneKey() {
+    wasm::WasmSignature Sig;
+    Sig.ReturnType = 2;
+    return Sig;
+  }
+  static unsigned getHashValue(const wasm::WasmSignature &Sig) {
+    unsigned H = hash_value(Sig.ReturnType);
+    for (int32_t Param : Sig.ParamTypes)
+      H = hash_combine(H, Param);
+    return H;
+  }
+  static bool isEqual(const wasm::WasmSignature &LHS,
+                      const wasm::WasmSignature &RHS) {
+    return LHS == RHS;
+  }
+};
+
+} // end namespace llvm
+
 namespace lld {
 namespace wasm {