diff --git a/clang/lib/Driver/ToolChains/AVR.cpp b/clang/lib/Driver/ToolChains/AVR.cpp
--- a/clang/lib/Driver/ToolChains/AVR.cpp
+++ b/clang/lib/Driver/ToolChains/AVR.cpp
@@ -369,16 +369,17 @@
     : Generic_ELF(D, Triple, Args) {
   GCCInstallation.init(Triple, Args);
 
+  std::string CPU = getCPUName(D, Args, Triple);
+  if (CPU.empty())
+    D.Diag(diag::warn_drv_avr_mcu_not_specified);
+
   // Only add default libraries if the user hasn't explicitly opted out.
   if (!Args.hasArg(options::OPT_nostdlib) &&
-      !Args.hasArg(options::OPT_nodefaultlibs)) {
-    if (GCCInstallation.isValid()) {
-      GCCInstallPath = GCCInstallation.getInstallPath();
-      std::string GCCParentPath(GCCInstallation.getParentLibPath());
-      getProgramPaths().push_back(GCCParentPath + "/../bin");
-    } else {
-      D.Diag(diag::warn_drv_avr_gcc_not_found);
-    }
+      !Args.hasArg(options::OPT_nodefaultlibs) &&
+      GCCInstallation.isValid()) {
+    GCCInstallPath = GCCInstallation.getInstallPath();
+    std::string GCCParentPath(GCCInstallation.getParentLibPath());
+    getProgramPaths().push_back(GCCParentPath + "/../bin");
   }
 }
 
@@ -448,22 +449,22 @@
   bool LinkStdlib = false;
   if (!Args.hasArg(options::OPT_nostdlib) &&
       !Args.hasArg(options::OPT_nodefaultlibs)) {
-    if (CPU.empty()) {
-      // We cannot link any standard libraries without an MCU specified.
-      D.Diag(diag::warn_drv_avr_mcu_not_specified);
-    } else {
-      Optional<StringRef> FamilyName = GetMCUFamilyName(CPU);
-      Optional<std::string> AVRLibcRoot = TC.findAVRLibcInstallation();
+    if (!CPU.empty()) {
+        Optional<StringRef> FamilyName = GetMCUFamilyName(CPU);
+        Optional<std::string> AVRLibcRoot = TC.findAVRLibcInstallation();
 
       if (!FamilyName) {
         // We do not have an entry for this CPU in the family
         // mapping table yet.
         D.Diag(diag::warn_drv_avr_family_linking_stdlibs_not_implemented)
             << CPU;
+      } else if (TC.getGCCInstallPath().empty()) {
+        // We can not link since there is no avr-ld.
+        D.Diag(diag::warn_drv_avr_gcc_not_found);
       } else if (!AVRLibcRoot) {
         // No avr-libc found and so no runtime linked.
         D.Diag(diag::warn_drv_avr_libc_not_found);
-      } else if (!TC.getGCCInstallPath().empty()) {
+      } else {
         std::string SubPath = GetMCUSubPath(CPU);
         CmdArgs.push_back(
             Args.MakeArgString(Twine("-L") + *AVRLibcRoot + "/lib/" + SubPath));
diff --git a/clang/test/Driver/avr-toolchain.c b/clang/test/Driver/avr-toolchain.c
--- a/clang/test/Driver/avr-toolchain.c
+++ b/clang/test/Driver/avr-toolchain.c
@@ -36,10 +36,25 @@
 // 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 -### --target=avr --sysroot=%S/Inputs/basic_avr_tree %s 2>&1 | FileCheck --check-prefix=WARN_STDLIB %s
-// RUN: %clang -### --target=avr --sysroot=%S/Inputs/basic_avr_tree -mmcu=atmega328 %s 2>&1 | FileCheck --check-prefix=NOWARN_STDLIB %s
-// RUN: %clang -### --target=avr --sysroot=%S/Inputs/basic_avr_tree -c %s 2>&1 | FileCheck --check-prefix=NOWARN_STDLIB %s
-
-// WARN_STDLIB: warning: no target microcontroller specified on command line, cannot link standard libraries, please pass -mmcu=<mcu name>
-// WARN_STDLIB: warning: standard library not linked and so no interrupt vector table or compiler runtime routines will be linked
-// NOWARN_STDLIB-NOT: warning:
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/basic_avr_tree -mmcu=atmega328 %s 2>&1 | FileCheck --check-prefix=NOWARN %s
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/basic_avr_tree -mmcu=atmega328 -S %s 2>&1 | FileCheck --check-prefix=NOWARN %s
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/ -mmcu=atmega328 -S %s 2>&1 | FileCheck --check-prefix=NOWARN %s
+// NOWARN-NOT: warning:
+
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/basic_avr_tree -S %s 2>&1 | FileCheck --check-prefixes=NOMCU,LINKA %s
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/ -S %s 2>&1 | FileCheck --check-prefixes=NOMCU,LINKA %s
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/basic_avr_tree %s 2>&1 | FileCheck --check-prefixes=NOMCU,LINKB %s
+// NOMCU: warning: no target microcontroller specified on command line, cannot link standard libraries, please pass -mmcu=<mcu name>
+// LINKB: warning: standard library not linked and so no interrupt vector table or compiler runtime routines will be linked
+// LINKB: warning: support for passing the data section address to the linker for microcontroller '' is not implemented
+// NOMCU-NOT: warning: {{.*}} avr-gcc
+// NOMCU-NOT: warning: {{.*}} avr-libc
+// LINKA-NOT: warning: {{.*}} interrupt vector
+// LINKA-NOT: warning: {{.*}} data section address
+
+// RUN: %clang -### --target=avr --sysroot=%S/Inputs/ -mmcu=atmega328 %s 2>&1 | FileCheck --check-prefixes=NOGCC %s
+// NOGCC: warning: no avr-gcc installation can be found on the system, cannot link standard libraries
+// NOGCC: warning: standard library not linked and so no interrupt vector table or compiler runtime routines will be linked
+// NOGCC-NOT: warning: {{.*}} microcontroller
+// NOGCC-NOT: warning: {{.*}} avr-libc
+// NOGCC-NOT: warning: {{.*}} data section address