diff --git a/clang/lib/Frontend/InitHeaderSearch.cpp b/clang/lib/Frontend/InitHeaderSearch.cpp
index e6cd823..d65d134 100644
--- a/clang/lib/Frontend/InitHeaderSearch.cpp
+++ b/clang/lib/Frontend/InitHeaderSearch.cpp
@@ -414,9 +414,11 @@
   default:
     break; // Everything else continues to use this routine's logic.
 
+  case llvm::Triple::Emscripten:
   case llvm::Triple::Linux:
   case llvm::Triple::Hurd:
   case llvm::Triple::Solaris:
+  case llvm::Triple::WASI:
     return;
 
   case llvm::Triple::Win32:
@@ -424,6 +426,12 @@
         triple.isOSBinFormatMachO())
       return;
     break;
+
+  case llvm::Triple::UnknownOS:
+    if (triple.getArch() == llvm::Triple::wasm32 ||
+        triple.getArch() == llvm::Triple::wasm64)
+      return;
+    break;
   }
 
   // All header search logic is handled in the Driver for Darwin.