diff --git a/lld/test/wasm/driver.s b/lld/test/wasm/driver.s
--- a/lld/test/wasm/driver.s
+++ b/lld/test/wasm/driver.s
@@ -5,6 +5,9 @@
   .functype _start () -> ()
   end_function
 
+# RUN: not wasm-ld %t -o 2>&1 | FileCheck --check-prefix=NO_O_VAL %s
+# NO_O_VAL: error: -o: missing argument
+
 # RUN: not wasm-ld -o %t.exe 2>&1 | FileCheck -check-prefix=IN %s
 # IN: error: no input files
 
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -184,6 +184,9 @@
   args = this->ParseArgs(vec, missingIndex, missingCount);
 
   handleColorDiagnostics(args);
+  if (missingCount)
+    error(Twine(args.getArgString(missingIndex)) + ": missing argument");
+
   for (auto *arg : args.filtered(OPT_UNKNOWN))
     error("unknown argument: " + arg->getAsString(args));
   return args;