Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1732,6 +1732,8 @@
   HelpText<"Add directory to SYSTEM framework search path, "
            "absolute paths are relative to -isysroot">,
   MetaVarName<"<directory>">, Flags<[CC1Option]>;
+def ignore_gcc : Joined<["--"], "ignore-gcc">, Flags<[DriverOption]>,
+  HelpText<"Don't look for gcc for finding a suitable sysroot">;
 def imacros : JoinedOrSeparate<["-", "--"], "imacros">, Group<clang_i_Group>, Flags<[CC1Option]>,
   HelpText<"Include macros from file before parsing">, MetaVarName<"<file>">;
 def image__base : Separate<["-"], "image_base">;
Index: lib/Driver/ToolChains/MinGW.cpp
===================================================================
--- lib/Driver/ToolChains/MinGW.cpp
+++ lib/Driver/ToolChains/MinGW.cpp
@@ -309,11 +309,14 @@
 
   if (getDriver().SysRoot.size())
     Base = getDriver().SysRoot;
-  else if (llvm::ErrorOr<std::string> GPPName = findGcc())
-    Base = llvm::sys::path::parent_path(
-        llvm::sys::path::parent_path(GPPName.get()));
-  else
-    Base = llvm::sys::path::parent_path(getDriver().getInstalledDir());
+  else {
+    llvm::ErrorOr<std::string> GPPName("");
+    if (!Args.hasArg(options::OPT_ignore_gcc) && (GPPName = findGcc()))
+      Base = llvm::sys::path::parent_path(
+          llvm::sys::path::parent_path(GPPName.get()));
+    else
+      Base = llvm::sys::path::parent_path(getDriver().getInstalledDir());
+  }
 
   Base += llvm::sys::path::get_separator();
   findGccLibDir();
Index: test/Driver/mingw-gcc.c
===================================================================
--- /dev/null
+++ test/Driver/mingw-gcc.c
@@ -0,0 +1,7 @@
+// RUN: env PATH=%S/Inputs/mingw_gcc/bin \
+// RUN:    %clang -target x86_64-w64-mingw32 -c -### %s 2>&1 | FileCheck -check-prefix=CHECK_MINGW_GCC %s
+// CHECK_MINGW_GCC: "{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}mingw_gcc{{/|\\\\}}x86_64-w64-mingw32{{/|\\\\}}include"
+
+// RUN: env PATH=%S/Inputs/mingw_gcc/bin \
+// RUN:    %clang -target x86_64-w64-mingw32 -c -### %s --ignore-gcc 2>&1 | FileCheck -check-prefix=CHECK_NOT_MINGW_GCC %s
+// CHECK_NOT_MINGW_GCC-NOT: "{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}mingw_gcc{{/|\\\\}}x86_64-w64-mingw32{{/|\\\\}}include"