Index: wasm/Config.h
===================================================================
--- wasm/Config.h
+++ wasm/Config.h
@@ -25,7 +25,9 @@
   bool AllowUndefined;
   bool CheckSignatures;
   bool Demangle;
+  bool GcSections;
   bool ImportMemory;
+  bool PrintGcSections;
   bool Relocatable;
   bool StripAll;
   bool StripDebug;
Index: wasm/Driver.cpp
===================================================================
--- wasm/Driver.cpp
+++ wasm/Driver.cpp
@@ -250,9 +250,14 @@
   Config->CheckSignatures =
       Args.hasFlag(OPT_check_signatures, OPT_no_check_signatures, false);
   Config->Entry = getEntry(Args, Args.hasArg(OPT_relocatable) ? "" : "_start");
+  errorHandler().FatalWarnings =
+      Args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
+  Config->GcSections = Args.hasFlag(OPT_gc_sections, OPT_no_gc_sections, false);
   Config->ImportMemory = Args.hasArg(OPT_import_memory);
   Config->OutputFile = Args.getLastArgValue(OPT_o);
   Config->Relocatable = Args.hasArg(OPT_relocatable);
+  Config->PrintGcSections =
+      Args.hasFlag(OPT_print_gc_sections, OPT_no_print_gc_sections, false);
   Config->SearchPaths = args::getStrings(Args, OPT_L);
   Config->StripAll = Args.hasArg(OPT_strip_all);
   Config->StripDebug = Args.hasArg(OPT_strip_debug);
@@ -274,13 +279,15 @@
   if (!Args.hasArg(OPT_INPUT))
     error("no input files");
 
-  if (Config->Relocatable && !Config->Entry.empty())
-    error("entry point specified for relocatable output file");
-  if (Config->Relocatable && Args.hasArg(OPT_undefined))
-    error("undefined symbols specified for relocatable output file");
-
   Symbol *EntrySym = nullptr;
-  if (!Config->Relocatable) {
+  if (Config->Relocatable) {
+    if (!Config->Entry.empty())
+      error("entry point specified for relocatable output file");
+    if (Config->GcSections)
+      error("-r and --gc-sections may not be used together");
+    if (Args.hasArg(OPT_undefined))
+      error("-r -and --undefined may not be used together");
+  } else {
     static WasmSignature Signature = {{}, WASM_TYPE_NORESULT};
     if (!Config->Entry.empty())
       EntrySym = Symtab->addUndefinedFunction(Config->Entry, &Signature);
Index: wasm/Options.td
===================================================================
--- wasm/Options.td
+++ wasm/Options.td
@@ -11,6 +11,7 @@
   def _eq: Joined<["--", "-"], name # "=">, Alias<!cast<Separate>(NAME)>;
 }
 
+// The follow flags are shared with the ELF linker
 def L: JoinedOrSeparate<["-"], "L">, MetaVarName<"<dir>">,
   HelpText<"Add a directory to the library search path">;
 
@@ -20,7 +21,18 @@
 def color_diagnostics_eq: J<"color-diagnostics=">,
   HelpText<"Use colors in diagnostics">;
 
-// The follow flags are shared with the ELF linker
+def entry: S<"entry">, MetaVarName<"<entry>">,
+  HelpText<"Name of entry point symbol">;
+
+def error_limit: J<"error-limit=">,
+  HelpText<"Maximum number of errors to emit before stopping (0 = no limit)">;
+
+def fatal_warnings: F<"fatal-warnings">,
+  HelpText<"Treat warnings as errors">;
+
+def gc_sections: F<"gc-sections">,
+  HelpText<"Enable garbage collection of unused sections">;
+
 def help: F<"help">, HelpText<"Print option help">;
 
 def l: JoinedOrSeparate<["-"], "l">, MetaVarName<"<libName>">,
@@ -34,20 +46,19 @@
 def no_color_diagnostics: F<"no-color-diagnostics">,
   HelpText<"Do not use colors in diagnostics">;
 
-def no_check_signatures: F<"no-check-signatures">, HelpText<"Don't check function signatures">;
+def no_fatal_warnings: F<"no-fatal-warnings">;
 
-def o: JoinedOrSeparate<["-"], "o">, MetaVarName<"<path>">,
-  HelpText<"Path to file to write output">;
-
-def threads: F<"threads">, HelpText<"Run the linker multi-threaded">;
+def no_gc_sections: F<"no-gc-sections">,
+  HelpText<"Disable garbage collection of unused sections">;
 
-def check_signatures: F<"check-signatures">, HelpText<"Check function signatures">;
-
-def v: Flag<["-"], "v">, HelpText<"Display the version number">;
+def no_print_gc_sections: F<"no-print-gc-sections">,
+  HelpText<"Do not list removed unused sections">;
 
-def version: F<"version">, HelpText<"Display the version number and exit">;
+def o: JoinedOrSeparate<["-"], "o">, MetaVarName<"<path>">,
+  HelpText<"Path to file to write output">;
 
-def verbose: F<"verbose">, HelpText<"Verbose mode">;
+def print_gc_sections: F<"print-gc-sections">,
+  HelpText<"List removed unused sections">;
 
 def relocatable: F<"relocatable">, HelpText<"Create relocatable object file">;
 
@@ -55,22 +66,23 @@
 
 def strip_debug: F<"strip-debug">, HelpText<"Strip debugging information">;
 
+def threads: F<"threads">, HelpText<"Run the linker multi-threaded">;
+
+def v: Flag<["-"], "v">, HelpText<"Display the version number">;
+
 defm undefined: Eq<"undefined">,
   HelpText<"Force undefined symbol during linking">;
 
-def z: JoinedOrSeparate<["-"], "z">, MetaVarName<"<option>">,
-  HelpText<"Linker option extensions">;
-
-def entry: S<"entry">, MetaVarName<"<entry>">,
-  HelpText<"Name of entry point symbol">;
+def version: F<"version">, HelpText<"Display the version number and exit">;
 
-def no_entry: F<"no-entry">,
-  HelpText<"Do not output any entry point">;
+def verbose: F<"verbose">, HelpText<"Verbose mode">;
 
-def error_limit: J<"error-limit=">,
-  HelpText<"Maximum number of errors to emit before stopping (0 = no limit)">;
+def z: JoinedOrSeparate<["-"], "z">, MetaVarName<"<option>">,
+  HelpText<"Linker option extensions">;
 
 // The follow flags are unique to wasm
+def check_signatures: F<"check-signatures">,
+  HelpText<"Check function signatures">;
 
 defm export: Eq<"export">,
   HelpText<"Force a symbol to be exported">;
@@ -81,6 +93,12 @@
 def initial_memory: J<"initial-memory=">,
   HelpText<"Initial size of the linear memory">;
 
+def no_check_signatures: F<"no-check-signatures">,
+  HelpText<"Don't check function signatures">;
+
+def no_entry: F<"no-entry">,
+  HelpText<"Do not output any entry point">;
+
 def max_memory: J<"max-memory=">,
   HelpText<"Maximum size of the linear memory">;