Index: COFF/Driver.cpp
===================================================================
--- COFF/Driver.cpp
+++ COFF/Driver.cpp
@@ -426,7 +426,7 @@
     case OPT_manifestuac:
       break;
     default:
-      OS << toString(Arg) << "\n";
+      OS << toString(*Arg) << "\n";
     }
   }
 
@@ -674,7 +674,7 @@
       break;
     case OPT_opt:
       if (!StringRef(Arg->getValue()).startswith("lld"))
-        Rsp += toString(Arg) + " ";
+        Rsp += toString(*Arg) + " ";
       break;
     case OPT_INPUT: {
       if (Optional<StringRef> Path = doFindFile(Arg->getValue())) {
@@ -686,7 +686,7 @@
       break;
     }
     default:
-      Rsp += toString(Arg) + "\n";
+      Rsp += toString(*Arg) + "\n";
     }
   }
 
Index: COFF/InputFiles.h
===================================================================
--- COFF/InputFiles.h
+++ COFF/InputFiles.h
@@ -58,7 +58,7 @@
   virtual ~InputFile() {}
 
   // Returns the filename.
-  StringRef getName() { return MB.getBufferIdentifier(); }
+  StringRef getName() const { return MB.getBufferIdentifier(); }
 
   // Reads a file (the constructor doesn't do that).
   virtual void parse() = 0;
@@ -229,7 +229,7 @@
 };
 } // namespace coff
 
-std::string toString(coff::InputFile *File);
+std::string toString(const coff::InputFile *File);
 } // namespace lld
 
 #endif
Index: COFF/InputFiles.cpp
===================================================================
--- COFF/InputFiles.cpp
+++ COFF/InputFiles.cpp
@@ -493,7 +493,7 @@
 }
 
 // Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)".
-std::string lld::toString(coff::InputFile *File) {
+std::string lld::toString(const coff::InputFile *File) {
   if (!File)
     return "<internal>";
   if (File->ParentName.empty())
Index: Common/Reproduce.cpp
===================================================================
--- Common/Reproduce.cpp
+++ Common/Reproduce.cpp
@@ -55,12 +55,12 @@
   return S;
 }
 
-std::string lld::toString(opt::Arg *Arg) {
-  std::string K = Arg->getSpelling();
-  if (Arg->getNumValues() == 0)
+std::string lld::toString(const opt::Arg &Arg) {
+  std::string K = Arg.getSpelling();
+  if (Arg.getNumValues() == 0)
     return K;
-  std::string V = quote(Arg->getValue());
-  if (Arg->getOption().getRenderStyle() == opt::Option::RenderJoinedStyle)
+  std::string V = quote(Arg.getValue());
+  if (Arg.getOption().getRenderStyle() == opt::Option::RenderJoinedStyle)
     return K + V;
   return K + " " + V;
 }
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -489,7 +489,7 @@
   return StripPolicy::Debug;
 }
 
-static uint64_t parseSectionAddress(StringRef S, opt::Arg *Arg) {
+static uint64_t parseSectionAddress(StringRef S, const opt::Arg &Arg) {
   uint64_t VA = 0;
   if (S.startswith("0x"))
     S = S.drop_front(2);
@@ -504,15 +504,15 @@
     StringRef Name;
     StringRef Addr;
     std::tie(Name, Addr) = StringRef(Arg->getValue()).split('=');
-    Ret[Name] = parseSectionAddress(Addr, Arg);
+    Ret[Name] = parseSectionAddress(Addr, *Arg);
   }
 
   if (auto *Arg = Args.getLastArg(OPT_Ttext))
-    Ret[".text"] = parseSectionAddress(Arg->getValue(), Arg);
+    Ret[".text"] = parseSectionAddress(Arg->getValue(), *Arg);
   if (auto *Arg = Args.getLastArg(OPT_Tdata))
-    Ret[".data"] = parseSectionAddress(Arg->getValue(), Arg);
+    Ret[".data"] = parseSectionAddress(Arg->getValue(), *Arg);
   if (auto *Arg = Args.getLastArg(OPT_Tbss))
-    Ret[".bss"] = parseSectionAddress(Arg->getValue(), Arg);
+    Ret[".bss"] = parseSectionAddress(Arg->getValue(), *Arg);
   return Ret;
 }
 
Index: ELF/DriverUtils.cpp
===================================================================
--- ELF/DriverUtils.cpp
+++ ELF/DriverUtils.cpp
@@ -166,7 +166,7 @@
          << "\n";
       break;
     default:
-      OS << toString(Arg) << "\n";
+      OS << toString(*Arg) << "\n";
     }
   }
   return Data.str();
Index: include/lld/Common/Reproduce.h
===================================================================
--- include/lld/Common/Reproduce.h
+++ include/lld/Common/Reproduce.h
@@ -33,7 +33,7 @@
 std::string rewritePath(StringRef S);
 
 // Returns the string form of the given argument.
-std::string toString(llvm::opt::Arg *Arg);
+std::string toString(const llvm::opt::Arg &Arg);
 }
 
 #endif
Index: wasm/InputFiles.h
===================================================================
--- wasm/InputFiles.h
+++ wasm/InputFiles.h
@@ -143,7 +143,7 @@
 
 } // namespace wasm
 
-std::string toString(wasm::InputFile *File);
+std::string toString(const wasm::InputFile *File);
 
 } // namespace lld
 
Index: wasm/InputFiles.cpp
===================================================================
--- wasm/InputFiles.cpp
+++ wasm/InputFiles.cpp
@@ -264,7 +264,7 @@
 }
 
 // Returns a string in the format of "foo.o" or "foo.a(bar.o)".
-std::string lld::toString(wasm::InputFile *File) {
+std::string lld::toString(const wasm::InputFile *File) {
   if (!File)
     return "<internal>";
 
Index: wasm/Symbols.h
===================================================================
--- wasm/Symbols.h
+++ wasm/Symbols.h
@@ -111,8 +111,8 @@
 } // namespace wasm
 
 // Returns a symbol name for an error message.
-std::string toString(wasm::Symbol &Sym);
-std::string toString(wasm::Symbol::Kind &Kind);
+std::string toString(const wasm::Symbol &Sym);
+std::string toString(wasm::Symbol::Kind Kind);
 
 } // namespace lld
 
Index: wasm/Symbols.cpp
===================================================================
--- wasm/Symbols.cpp
+++ wasm/Symbols.cpp
@@ -76,11 +76,11 @@
 
 bool Symbol::isHidden() const { return Sym && Sym->isHidden(); }
 
-std::string lld::toString(wasm::Symbol &Sym) {
+std::string lld::toString(const wasm::Symbol &Sym) {
   return wasm::displayName(Sym.getName());
 }
 
-std::string lld::toString(wasm::Symbol::Kind &Kind) {
+std::string lld::toString(wasm::Symbol::Kind Kind) {
   switch (Kind) {
   case wasm::Symbol::DefinedFunctionKind:
     return "DefinedFunction";