Index: lib/Driver/ToolChains/WebAssembly.cpp
===================================================================
--- lib/Driver/ToolChains/WebAssembly.cpp
+++ lib/Driver/ToolChains/WebAssembly.cpp
@@ -63,6 +63,8 @@
   Args.AddAllArgs(CmdArgs, options::OPT_L);
   ToolChain.AddFilePathLibArgs(Args, CmdArgs);
 
+  CmdArgs.push_back("-allow-undefined-file");
+  CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("syms.def")));
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles)) {
     if (Args.hasArg(options::OPT_shared))
       CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("rcrt1.o")));