diff --git a/llvm/include/llvm/Support/CommandLine.h b/llvm/include/llvm/Support/CommandLine.h
--- a/llvm/include/llvm/Support/CommandLine.h
+++ b/llvm/include/llvm/Support/CommandLine.h
@@ -1205,7 +1205,11 @@
 };
 
 template <> struct applicator<MiscFlags> {
-  static void opt(MiscFlags MF, Option &O) { O.setMiscFlag(MF); }
+  static void opt(MiscFlags MF, Option &O) {
+    assert((MF != Grouping || O.ArgStr.size() == 1) &&
+           "cl::Grouping can only apply to single charater Options.");
+    O.setMiscFlag(MF);
+  }
 };
 
 // apply method - Apply modifiers to an option in a type safe way.
diff --git a/llvm/lib/Support/CommandLine.cpp b/llvm/lib/Support/CommandLine.cpp
--- a/llvm/lib/Support/CommandLine.cpp
+++ b/llvm/lib/Support/CommandLine.cpp
@@ -408,6 +408,8 @@
     GlobalParser->updateArgStr(this, S);
   assert((S.empty() || S[0] != '-') && "Option can't start with '-");
   ArgStr = S;
+  if (ArgStr.size() == 1)
+    setMiscFlag(Grouping);
 }
 
 void Option::reset() {
diff --git a/llvm/test/tools/llvm-readobj/merged.test b/llvm/test/tools/llvm-readobj/merged.test
--- a/llvm/test/tools/llvm-readobj/merged.test
+++ b/llvm/test/tools/llvm-readobj/merged.test
@@ -10,4 +10,4 @@
 RUN: not llvm-readobj -aeWhSrnudlVgIs %p/Inputs/trivial.obj.elf-i386 2>&1 | FileCheck %s --check-prefix=UNKNOWN
 
 CHECK-NOT: Unknown command line argument
-UNKNOWN:   Unknown command line argument
+UNKNOWN:   for the --section-headers option: may only occur zero or one times!