Index: cfe/trunk/include/clang/Driver/ToolChain.h
===================================================================
--- cfe/trunk/include/clang/Driver/ToolChain.h
+++ cfe/trunk/include/clang/Driver/ToolChain.h
@@ -78,6 +78,10 @@
                   bool IsRegistered)
       : TargetPrefix(Target), ModeSuffix(Suffix), DriverMode(Mode),
         TargetIsValid(IsRegistered) {}
+
+  bool isEmpty() const {
+    return TargetPrefix.empty() && ModeSuffix.empty() && DriverMode == nullptr;
+  }
 };
 
 /// ToolChain - Access to tools for a single platform.
Index: cfe/trunk/lib/Driver/Driver.cpp
===================================================================
--- cfe/trunk/lib/Driver/Driver.cpp
+++ cfe/trunk/lib/Driver/Driver.cpp
@@ -129,7 +129,8 @@
 
 void Driver::ParseDriverMode(StringRef ProgramName,
                              ArrayRef<const char *> Args) {
-  ClangNameParts = ToolChain::getTargetAndModeFromProgramName(ProgramName);
+  if (ClangNameParts.isEmpty())
+    ClangNameParts = ToolChain::getTargetAndModeFromProgramName(ProgramName);
   setDriverModeFromOption(ClangNameParts.DriverMode);
 
   for (const char *ArgPtr : Args) {
Index: cfe/trunk/test/Driver/config-file3.c
===================================================================
--- cfe/trunk/test/Driver/config-file3.c
+++ cfe/trunk/test/Driver/config-file3.c
@@ -27,6 +27,14 @@
 // FULL-NAME: -Wundefined-func-template
 // FULL-NAME-NOT: -Werror
 //
+//--- Invocation qqq-clang-g++ tries to find config file qqq-clang-g++.cfg even without -no-canonical-prefixes.
+// (As the clang executable and symlink are in different directories, this
+// requires specifying the path via --config-*-dir= though.)
+//
+// RUN: %T/testdmode/qqq-clang-g++ --config-system-dir= --config-user-dir=%T/testdmode -c %s -### 2>&1 | FileCheck %s -check-prefix SYMLINK
+//
+// SYMLINK: Configuration file: {{.*}}/testdmode/qqq-clang-g++.cfg
+//
 //--- File specified by --config overrides config inferred from clang executable.
 //
 // RUN: %T/testdmode/qqq-clang-g++ --config-system-dir=%S/Inputs/config --config-user-dir= --config i386-qqq -c -no-canonical-prefixes %s -### 2>&1 | FileCheck %s -check-prefix CHECK-EXPLICIT