diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index 27e8095534a65..5cdc573ac2466 100644
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -214,6 +214,44 @@ if(GCC_INSTALL_PREFIX AND NOT USE_DEPRECATED_GCC_INSTALL_PREFIX)
     "See https://github.com/llvm/llvm-project/pull/77537 for detail.")
 endif()
 
+cmake_dependent_option(CLANG_USE_XCSELECT "Use libxcselect to find the macOS SDK." OFF "APPLE" OFF)
+
+if(CLANG_USE_XCSELECT)
+  if(DEFAULT_SYSROOT)
+    message(FATAL_ERROR "Setting DEFAULT_SYSROOT is incompatible with CLANG_USE_XCSELECT.")
+  endif()
+
+  check_include_file(xcselect.h CLANG_HAVE_XCSELECT_H)
+  if(NOT CLANG_HAVE_XCSELECT_H)
+    message(FATAL_ERROR "CLANG_USE_XCSELECT is enabled but xcselect.h was not found.")
+  endif()
+
+  include(CheckSymbolExists)
+  list(APPEND CMAKE_REQUIRED_LIBRARIES xcselect)
+  check_symbol_exists(xcselect_host_sdk_path xcselect.h CLANG_HAVE_XCSELECT_HOST_SDK_PATH)
+  list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES xcselect)
+
+  if(NOT CLANG_HAVE_XCSELECT_HOST_SDK_PATH)
+    message(FATAL_ERROR "CLANG_USE_XCSELECT is enabled but either libxcselect is not available "
+      "or it is missing xcselect_host_sdk_path.")
+  endif()
+
+  set(XCSELECT_VALID_POLICIES LATEST MATCHING_ONLY MATCHING_PREFERRED)
+  set(CLANG_XCSELECT_HOST_SDK_POLICY "LATEST" CACHE STRING
+    "Policy to use for xcselect. One of: ${XCSELECT_VALID_POLICIES}")
+  set_property(CACHE CLANG_XCSELECT_HOST_SDK_POLICY PROPERTY STRINGS ${XCSELECT_VALID_POLICIES})
+  string(TOUPPER ${CLANG_XCSELECT_HOST_SDK_POLICY} CLANG_XCSELECT_HOST_SDK_POLICY)
+  list(JOIN XCSELECT_VALID_POLICIES "|" XCSELECT_POLICY_REGEX)
+
+  if(NOT CLANG_XCSELECT_HOST_SDK_POLICY MATCHES "^XCSELECT_HOST_SDK_POLICY_(${XCSELECT_POLICY_REGEX})$")
+    if(NOT CLANG_XCSELECT_HOST_SDK_POLICY IN_LIST XCSELECT_VALID_POLICIES)
+      message(FATAL_ERROR
+        "CLANG_XCSELECT_HOST_SDK_POLICY (${CLANG_XCSELECT_HOST_SDK_POLICY}) must be one of: ${XCSELECT_VALID_POLICIES}")
+    endif()
+    set(CLANG_XCSELECT_HOST_SDK_POLICY "XCSELECT_HOST_SDK_POLICY_${CLANG_XCSELECT_HOST_SDK_POLICY}")
+  endif()
+endif()
+
 set(ENABLE_LINKER_BUILD_ID OFF CACHE BOOL "pass --build-id to ld")
 
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL
diff --git a/clang/include/clang/Config/config.h.cmake b/clang/include/clang/Config/config.h.cmake
index 27ed69e21562b..9ae0c6a4b9e11 100644
--- a/clang/include/clang/Config/config.h.cmake
+++ b/clang/include/clang/Config/config.h.cmake
@@ -86,4 +86,10 @@
 /* Whether CIR is built into Clang */
 #cmakedefine01 CLANG_ENABLE_CIR
 
+/* Whether to use xcselect to find the macOS SDK */
+#cmakedefine CLANG_USE_XCSELECT
+
+/* Policy to use for xcselect */
+#cmakedefine CLANG_XCSELECT_HOST_SDK_POLICY ${CLANG_XCSELECT_HOST_SDK_POLICY}
+
 #endif
diff --git a/clang/lib/Driver/CMakeLists.txt b/clang/lib/Driver/CMakeLists.txt
index 4fd10bf671512..299de2ef30470 100644
--- a/clang/lib/Driver/CMakeLists.txt
+++ b/clang/lib/Driver/CMakeLists.txt
@@ -14,6 +14,10 @@ if(WIN32)
   set(system_libs version)
 endif()
 
+if(CLANG_USE_XCSELECT)
+  set(system_libs xcselect)
+endif()
+
 add_clang_library(clangDriver
   Action.cpp
   Compilation.cpp
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 87380869f6fda..ed292dfa62e10 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -29,6 +29,10 @@
 #include "llvm/TargetParser/Triple.h"
 #include <cstdlib> // ::getenv
 
+#ifdef CLANG_USE_XCSELECT
+#include <xcselect.h> // ::xcselect_host_sdk_path
+#endif
+
 using namespace clang::driver;
 using namespace clang::driver::tools;
 using namespace clang::driver::toolchains;
@@ -2257,17 +2261,27 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
     // Warn if the path does not exist.
     if (!getVFS().exists(A->getValue()))
       getDriver().Diag(clang::diag::warn_missing_sysroot) << A->getValue();
-  } else {
-    if (char *env = ::getenv("SDKROOT")) {
-      // We only use this value as the default if it is an absolute path,
-      // exists, and it is not the root path.
-      if (llvm::sys::path::is_absolute(env) && getVFS().exists(env) &&
-          StringRef(env) != "/") {
-        Args.append(Args.MakeSeparateArg(
-            nullptr, Opts.getOption(options::OPT_isysroot), env));
-      }
+  } else if (const char *env = ::getenv("SDKROOT")) {
+    // We only use this value as the default if it is an absolute path,
+    // exists, and it is not the root path.
+    if (llvm::sys::path::is_absolute(env) && getVFS().exists(env) &&
+        StringRef(env) != "/") {
+      Args.append(Args.MakeSeparateArg(
+          nullptr, Opts.getOption(options::OPT_isysroot), env));
     }
   }
+#ifdef CLANG_USE_XCSELECT
+  // FIXME: This should check for `getTriple().isMacOSX()`, but this breaks
+  // many tests. See https://github.com/llvm/llvm-project/pull/119670.
+  else if (getTriple().getOS() == llvm::Triple::MacOSX) {
+    char *p;
+    if (!::xcselect_host_sdk_path(CLANG_XCSELECT_HOST_SDK_POLICY, &p)) {
+      Args.append(Args.MakeSeparateArg(
+          nullptr, Opts.getOption(options::OPT_isysroot), p));
+      ::free(p);
+    }
+  }
+#endif
 
   // Read the SDKSettings.json file for more information, like the SDK version
   // that we can pass down to the compiler.
diff --git a/clang/test/CMakeLists.txt b/clang/test/CMakeLists.txt
index 5369dc92f69e8..78ef8bc6e690a 100644
--- a/clang/test/CMakeLists.txt
+++ b/clang/test/CMakeLists.txt
@@ -10,6 +10,7 @@ llvm_canonicalize_cmake_booleans(
   CLANG_PLUGIN_SUPPORT
   CLANG_SPAWN_CC1
   CLANG_ENABLE_CIR
+  CLANG_USE_XCSELECT
   ENABLE_BACKTRACES
   LLVM_BUILD_EXAMPLES
   LLVM_BYE_LINK_INTO_TOOLS
diff --git a/clang/test/Driver/darwin-ld-platform-version-macos-nosdk.c b/clang/test/Driver/darwin-ld-platform-version-macos-nosdk.c
new file mode 100644
index 0000000000000..c5e0dd94c5925
--- /dev/null
+++ b/clang/test/Driver/darwin-ld-platform-version-macos-nosdk.c
@@ -0,0 +1,12 @@
+// UNSUPPORTED: xcselect
+// CLANG_USE_XCSELECT will always have an SDK inferred.
+
+// RUN: touch %t.o
+
+// RUN: %clang -target x86_64-apple-macos10.13 -mlinker-version=520 \
+// RUN:   -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=NOSDK %s
+// RUN: %clang -target x86_64-apple-darwin17 -mlinker-version=520 \
+// RUN:   -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=NOSDK %s
+// NOSDK: "-platform_version" "macos" "10.13.0" "10.13.0"
diff --git a/clang/test/Driver/darwin-ld-platform-version-macos.c b/clang/test/Driver/darwin-ld-platform-version-macos.c
index 355df8dfc1bc2..0804c850242c2 100644
--- a/clang/test/Driver/darwin-ld-platform-version-macos.c
+++ b/clang/test/Driver/darwin-ld-platform-version-macos.c
@@ -43,8 +43,8 @@
 
 // RUN: %clang -target x86_64-apple-macos10.13 -mlinker-version=520 \
 // RUN:   -### %t.o 2>&1 \
-// RUN:   | FileCheck --check-prefix=NOSDK %s
+// RUN:   | FileCheck --check-prefix=INFERRED-SDK %s
 // RUN: %clang -target x86_64-apple-darwin17 -mlinker-version=520 \
 // RUN:   -### %t.o 2>&1 \
-// RUN:   | FileCheck --check-prefix=NOSDK %s
-// NOSDK: "-platform_version" "macos" "10.13.0" "10.13.0"
+// RUN:   | FileCheck --check-prefix=INFERRED-SDK %s
+// INFERRED-SDK: "-platform_version" "macos" "10.13.0" "{{[0-9]+(\.[0-9]+)*}}"
diff --git a/clang/test/Driver/xcselect.c b/clang/test/Driver/xcselect.c
new file mode 100644
index 0000000000000..01cd4aca5ec23
--- /dev/null
+++ b/clang/test/Driver/xcselect.c
@@ -0,0 +1,5 @@
+// REQUIRES: xcselect
+// RUN: %clang -target arm64-apple-macosx -c -### %s 2> %t.log
+// RUN: FileCheck %s <%t.log
+
+// CHECK: "-isysroot" "{{.*}}/SDKs/MacOSX{{([0-9]+(\.[0-9]+)?)?}}.sdk"
diff --git a/clang/test/lit.cfg.py b/clang/test/lit.cfg.py
index 7e7934d5fe0f5..aadc9f85a168b 100644
--- a/clang/test/lit.cfg.py
+++ b/clang/test/lit.cfg.py
@@ -338,6 +338,8 @@ def calculate_arch_features(arch_string):
 if config.have_llvm_driver:
     config.available_features.add("llvm-driver")
 
+if config.use_xcselect:
+    config.available_features.add("xcselect")
 
 # Some tests perform deep recursion, which requires a larger pthread stack size
 # than the relatively low default of 192 KiB for 64-bit processes on AIX. The
diff --git a/clang/test/lit.site.cfg.py.in b/clang/test/lit.site.cfg.py.in
index 1cbd876ac5bb9..95b3a866f64b3 100644
--- a/clang/test/lit.site.cfg.py.in
+++ b/clang/test/lit.site.cfg.py.in
@@ -44,6 +44,7 @@ config.standalone_build = @CLANG_BUILT_STANDALONE@
 config.ppc_linux_default_ieeelongdouble = @PPC_LINUX_DEFAULT_IEEELONGDOUBLE@
 config.have_llvm_driver = @LLVM_TOOL_LLVM_DRIVER_BUILD@
 config.substitutions.append(("%llvm-version-major", "@LLVM_VERSION_MAJOR@"))
+config.use_xcselect = @CLANG_USE_XCSELECT@
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)