diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -410,6 +410,17 @@
   Args.AddAllArgs(CmdArgs, options::OPT_sub__library);
   Args.AddAllArgs(CmdArgs, options::OPT_sub__umbrella);
 
+  // Pass -L <toolchain-install>/bin/../lib/ to linker to prioritize toolchain's
+  // libc++.dylib over the sysroot-provided one. This matches what we do for
+  // determining which libc++ headers to use.
+  llvm::SmallString<128> InstallBinPath =
+      llvm::StringRef(D.getInstalledDir()); // <install>/bin
+  llvm::SmallString<128> LibCxxDylibDirPath = InstallBinPath;
+  llvm::sys::path::append(LibCxxDylibDirPath, "..",
+                          "lib"); // <install>/bin/../lib
+  CmdArgs.push_back("-L");
+  CmdArgs.push_back(C.getArgs().MakeArgString(LibCxxDylibDirPath));
+
   // Give --sysroot= preference, over the Apple specific behavior to also use
   // --isysroot as the syslibroot.
   StringRef sysroot = C.getSysRoot();
diff --git a/clang/test/Driver/darwin-header-search-libcxx.cpp b/clang/test/Driver/darwin-header-search-libcxx.cpp
--- a/clang/test/Driver/darwin-header-search-libcxx.cpp
+++ b/clang/test/Driver/darwin-header-search-libcxx.cpp
@@ -116,7 +116,7 @@
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:     -stdlib=platform \
 // RUN:     -nostdinc++ \
-// RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr \
+// RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
 // RUN:               --check-prefix=CHECK-LIBCXX-NOSTDINCXX %s
 // CHECK-LIBCXX-NOSTDINCXX: "-cc1"
diff --git a/clang/test/Driver/darwin-header-search-libcxx.cpp b/clang/test/Driver/darwin-link-libcxx-from-toolchain.cpp
copy from clang/test/Driver/darwin-header-search-libcxx.cpp
copy to clang/test/Driver/darwin-link-libcxx-from-toolchain.cpp
--- a/clang/test/Driver/darwin-header-search-libcxx.cpp
+++ b/clang/test/Driver/darwin-link-libcxx-from-toolchain.cpp
@@ -1,63 +1,48 @@
 // UNSUPPORTED: system-windows
 
-// General tests that the header search paths for libc++ detected by the driver
-// and passed to CC1 are correct on Darwin platforms.
+// Tests to check that we pass -L <install>/bin/../lib/ to the linker to prioritize the toolchain's libc++.dylib over system's libc++.tbd in all cases.
 
 // Check without a sysroot and without headers alongside the installation
-// (no include path should be added, and no warning or error).
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
-// RUN:   | FileCheck --check-prefix=CHECK-LIBCXX-NONE %s
-// CHECK-LIBCXX-NONE: "-cc1"
+// RUN:   | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-2 %s
 
 // Check with only headers alongside the installation (those should be used).
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
 // RUN:     --sysroot="" \
 // RUN:   | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-TOOLCHAIN-1 %s
-// CHECK-LIBCXX-TOOLCHAIN-1: "-cc1"
-// CHECK-LIBCXX-TOOLCHAIN-1: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-TOOLCHAIN-1-NOT: "-internal-isystem" "/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_no_libcxx \
 // RUN:   | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
 // RUN:               -DSYSROOT=%S/Inputs/basic_darwin_sdk_no_libcxx \
-// RUN:               --check-prefix=CHECK-LIBCXX-TOOLCHAIN-2 %s
-// CHECK-LIBCXX-TOOLCHAIN-2: "-cc1"
-// CHECK-LIBCXX-TOOLCHAIN-2: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-TOOLCHAIN-2-NOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 
 // Check with only headers in the sysroot (those should be used).
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx \
-// RUN:               --check-prefix=CHECK-LIBCXX-SYSROOT-1 %s
-// CHECK-LIBCXX-SYSROOT-1: "-cc1"
-// CHECK-LIBCXX-SYSROOT-1: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
-// CHECK-LIBCXX-SYSROOT-1-NOT: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 
 // Check with both headers in the sysroot and headers alongside the installation
-// (the headers in the toolchain should be preferred over the <sysroot> headers).
-// Ensure that both -isysroot and --sysroot work, and that isysroot has precedence
-// over --sysroot.
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
@@ -65,9 +50,9 @@
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1 %s
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
@@ -75,9 +60,9 @@
 // RUN:     --sysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1 %s
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
@@ -86,16 +71,13 @@
 // RUN:     --sysroot %S/Inputs/basic_darwin_sdk_no_libcxx \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1 %s
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1: "-cc1"
-// CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1-NOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
 
 // Make sure that using -nostdinc, -nostdinc++ or -nostdlib will drop both the toolchain
 // C++ include path and the sysroot one.
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin16 \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
@@ -104,26 +86,20 @@
 // RUN:     -nostdinc \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-NOSTDLIBINC %s
-// CHECK-LIBCXX-NOSTDINC: "-cc1"
-// CHECK-LIBCXX-NOSTDINC-NOT: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-NOSTDINC-NOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin16 \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:     -stdlib=platform \
 // RUN:     -nostdinc++ \
-// RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr \
+// RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-NOSTDINCXX %s
-// CHECK-LIBCXX-NOSTDINCXX: "-cc1"
-// CHECK-LIBCXX-NOSTDINCXX-NOT: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-NOSTDINCXX-NOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin16 \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
@@ -132,43 +108,38 @@
 // RUN:     -nostdlibinc \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN:               --check-prefix=CHECK-LIBCXX-NOSTDLIBINC %s
-// CHECK-LIBCXX-NOSTDLIBINC: "-cc1"
-// CHECK-LIBCXX-NOSTDLIBINC-NOT: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-NOSTDLIBINC-NOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 
 // Make sure we explain that we considered a path but didn't add it when it
 // doesn't exist.
 //
-// RUN: %clang %s -fsyntax-only -v 2>&1 \
+// RUN: %clang -### %s -v 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk \
 // RUN:     -stdlib=libc++ \
 // RUN:   | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx \
-// RUN:               --check-prefix=CHECK-LIBCXX-MISSING-TOOLCHAIN %s
-// CHECK-LIBCXX-MISSING-TOOLCHAIN: ignoring nonexistent directory "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 //
-// RUN: %clang %s -fsyntax-only -v 2>&1 \
+// RUN: %clang -### %s -v 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_no_libcxx \
 // RUN:     -stdlib=libc++ \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_no_libcxx \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx \
-// RUN:               --check-prefix=CHECK-LIBCXX-MISSING-BOTH %s
-// CHECK-LIBCXX-MISSING-BOTH: ignoring nonexistent directory "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
-// CHECK-LIBCXX-MISSING-BOTH: ignoring nonexistent directory "[[SYSROOT]]/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
 
 // Make sure that on Darwin, we use libc++ header search paths by default even when
 // -stdlib= isn't passed.
 //
-// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-apple-darwin \
 // RUN:     -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
 // RUN:     -isysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:   | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
 // RUN:               -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx \
-// RUN:               --check-prefix=CHECK-LIBCXX-STDLIB-UNSPECIFIED %s
-// CHECK-LIBCXX-STDLIB-UNSPECIFIED: "-cc1"
-// CHECK-LIBCXX-STDLIB-UNSPECIFIED: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// RUN:               --check-prefix=CHECK-TOOLCHAIN-LIBCXX-LINKING-1 %s
+
+// CHECK-TOOLCHAIN-LIBCXX-LINKING-1: "/usr/bin/ld"
+// CHECK-TOOLCHAIN-LIBCXX-LINKING-1: "-L" "[[TOOLCHAIN]]/usr/bin/../lib"