Index: clang/lib/Driver/ToolChains/WebAssembly.cpp
===================================================================
--- clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -533,5 +533,10 @@
   }
 
   // Second add the generic one.
-  addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version);
+  std::string VersionPath = LibPath + "/c++/" + Version;
+  std::string VersionPathArch = VersionPath;
+  VersionPathArch.push_back('/');
+  VersionPathArch.append(MultiarchTriple);
+  addSystemInclude(DriverArgs, CC1Args, VersionPathArch);
+  addSystemInclude(DriverArgs, CC1Args, VersionPath);
 }