diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2410,6 +2410,8 @@
   for (const Arg *A :
        Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler,
                      options::OPT_mimplicit_it_EQ)) {
+    A->claim();
+
     if (A->getOption().getID() == options::OPT_mimplicit_it_EQ) {
       switch (C.getDefaultToolChain().getArch()) {
       case llvm::Triple::arm:
@@ -2427,8 +2429,6 @@
       }
     }
 
-    A->claim();
-
     for (StringRef Value : A->getValues()) {
       if (TakeNextArg) {
         CmdArgs.push_back(Value.data());
diff --git a/clang/test/Driver/arm-target-as-mimplicit-it.s b/clang/test/Driver/arm-target-as-mimplicit-it.s
--- a/clang/test/Driver/arm-target-as-mimplicit-it.s
+++ b/clang/test/Driver/arm-target-as-mimplicit-it.s
@@ -35,6 +35,8 @@
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=always,-mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=INVALID
 
 
+/// Check that the argument we ignore is still marked as used.
+// ALWAYS-NOT: warning: argument unused during compilation: {{.*}}-mimplicit-it={{.*}}
 /// Check that there isn't a second -arm-implicit-it before or after the one
 /// that was the indended match.
 // ALWAYS-NOT: "-arm-implicit-it={{.*}}"