diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -490,7 +490,18 @@
 std::string ToolChain::getRuntimePath() const {
   SmallString<128> P(D.ResourceDir);
   llvm::sys::path::append(P, "lib", getTripleString());
-  return std::string(P.str());
+  std::string Ret(P);
+  // When LLVM_DEFAULT_TARGET_TRIPLE uses Debian multiarch style
+  // "x86_64-linux-gnu" (no vendor part), use the unnormalized
+  // D.getTargetTriple() instead of the normalized getTripleString()
+  // ("x86_64-unknown-linux-gnu").
+  if (!getVFS().exists(Ret)) {
+    P.clear();
+    llvm::sys::path::append(P, D.ResourceDir, "lib", D.getTargetTriple());
+    if (getVFS().exists(P))
+      Ret = std::string(P);
+  }
+  return Ret;
 }
 
 std::string ToolChain::getStdlibPath() const {
diff --git a/clang/test/Driver/linux-per-target-runtime-dir.c b/clang/test/Driver/linux-per-target-runtime-dir.c
--- a/clang/test/Driver/linux-per-target-runtime-dir.c
+++ b/clang/test/Driver/linux-per-target-runtime-dir.c
@@ -25,3 +25,10 @@
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:   | FileCheck --check-prefix=CHECK-FILE-NAME-X8664 %s
 // CHECK-FILE-NAME-X8664: lib{{/|\\}}x86_64-unknown-linux-gnu{{/|\\}}libclang_rt.builtins.a
+
+/// On Debian, LLVM_DEFAULT_TARGET_TRIPLE may use Debian multiarch style "x86_64-linux-gnu".
+// RUN: %clangxx -### %s --target=x86_64-linux-gnu --sysroot=%S/Inputs/basic_linux_libcxx_tree \
+// RUN:   -ccc-install-dir %S/Inputs/basic_linux_libcxx_tree/usr/bin \
+// RUN:   -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir_debian \
+// RUN:   --rtlib=compiler-rt 2>&1 | FileCheck --check-prefix=CHECK-DEBIAN-X8664 %s
+// CHECK-DEBIAN-X8664: lib{{/|\\}}x86_64-linux-gnu{{/|\\}}libclang_rt.builtins.a