Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -127,7 +127,10 @@
       set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
     endif()
   else(FUCHSIA OR UNIX)
-    MESSAGE(SEND_ERROR "Unable to determine platform")
+    if(${CMAKE_SYSTEM_NAME} MATCHES "Wasi")
+    else()
+      MESSAGE(SEND_ERROR "Unable to determine platform")
+    endif()
   endif(FUCHSIA OR UNIX)
 endif(WIN32)