1 files changed, 20 insertions, 2 deletions
diff --git a/clang/lib/Driver/Distro.cpp b/clang/lib/Driver/Distro.cpp
index 92e04108a7e..06707fefc9d 100644
--- a/clang/lib/Driver/Distro.cpp
+++ b/clang/lib/Driver/Distro.cpp
@@ -13,11 +13,28 @@
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/ADT/Triple.h"
 
 using namespace clang::driver;
 using namespace clang;
 
-static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
+static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS,
+                                       const llvm::Triple &TargetOrHost) {
+  // If we don't target Linux, no need to check the distro. This saves a few
+  // OS calls.
+  if (!TargetOrHost.isOSLinux())
+    return Distro::UnknownDistro;
+
+  // If the host is not running Linux, and we're backed by a real file system,
+  // no need to check the distro. This is the case where someone is
+  // cross-compiling from BSD or Windows to Linux, and it would be meaningless
+  // to try to figure out the "distro" of the non-Linux host.
+  IntrusiveRefCntPtr<llvm::vfs::FileSystem> RealFS =
+      llvm::vfs::getRealFileSystem();
+  llvm::Triple HostTriple(llvm::sys::getProcessTriple());
+  if (!HostTriple.isOSLinux() && &VFS == RealFS.get())
+    return Distro::UnknownDistro;
+
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
       VFS.getBufferForFile("/etc/lsb-release");
   if (File) {
@@ -149,4 +166,5 @@ static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
   return Distro::UnknownDistro;
 }
 
-Distro::Distro(llvm::vfs::FileSystem &VFS) : DistroVal(DetectDistro(VFS)) {}
+Distro::Distro(llvm::vfs::FileSystem &VFS, const llvm::Triple &TargetOrHost)
+    : DistroVal(DetectDistro(VFS, TargetOrHost)) {}