Index: clang/lib/Driver/ToolChains/AVR.cpp
===================================================================
--- clang/lib/Driver/ToolChains/AVR.cpp
+++ clang/lib/Driver/ToolChains/AVR.cpp
@@ -372,6 +372,7 @@
   // Only add default libraries if the user hasn't explicitly opted out.
   if (!Args.hasArg(options::OPT_nostdlib) &&
       !Args.hasArg(options::OPT_nodefaultlibs) &&
+      !Args.hasArg(options::OPT_S) &&
       !Args.hasArg(options::OPT_c /* does not apply when not linking */)) {
     std::string CPU = getCPUName(D, Args, Triple);
 
Index: clang/test/Driver/avr-toolchain.c
===================================================================
--- clang/test/Driver/avr-toolchain.c
+++ clang/test/Driver/avr-toolchain.c
@@ -35,3 +35,10 @@
 // RUN: %clang %s -### -target avr --sysroot %S/Inputs/basic_avr_tree 2>&1 -nostdinc | FileCheck --check-prefix=NOSTDINC %s
 // RUN: %clang %s -### -target avr --sysroot %S/Inputs/basic_avr_tree 2>&1 -nostdlibinc | FileCheck --check-prefix=NOSTDINC %s
 // NOSTDINC-NOT: "-internal-isystem" {{".*avr/include"}}
+
+// RUN: %clang %s -### -target avr --sysroot %S/Inputs/basic_avr_tree 2>&1 | FileCheck --check-prefix=LINK %s
+// LINK: warning: standard library not linked and so no interrupt vector table or compiler runtime routines will be linked
+
+// RUN: %clang %s -### -target avr --sysroot %S/Inputs/basic_avr_tree -S 2>&1 | FileCheck --check-prefix=NOLINK %s
+// RUN: %clang %s -### -target avr --sysroot %S/Inputs/basic_avr_tree -c 2>&1 | FileCheck --check-prefix=NOLINK %s
+// NOLINK-NOT: warning: standard library not linked and so no interrupt vector table or compiler runtime routines will be linked