Index: cmake/config-ix.cmake
===================================================================
--- cmake/config-ix.cmake
+++ cmake/config-ix.cmake
@@ -208,6 +208,32 @@
   endif()
 endmacro()
 
+# Returns CFLAGS that should be used to run tests for the
+# specific apple platform and architecture.
+function(get_test_cflags_for_apple_platform platform arch cflags_out)
+  is_valid_apple_platform("${platform}" is_valid_platform)
+  if (NOT is_valid_platform)
+    message(FATAL_ERROR "\"${platform}\" is not a valid apple platform")
+  endif()
+  set(test_cflags "")
+  get_target_flags_for_arch(${arch} test_cflags)
+  list(APPEND test_cflags ${DARWIN_${platform}_CFLAGS})
+  string(REPLACE ";" " " test_cflags_str "${test_cflags}")
+  string(APPEND test_cflags_str "${COMPILER_RT_TEST_COMPILER_CFLAGS}")
+  set(${cflags_out} "${test_cflags_str}" PARENT_SCOPE)
+endfunction()
+
+function(is_valid_apple_platform platform is_valid_out)
+  set(is_valid FALSE)
+  if ("${platform}" STREQUAL "")
+    message(FATAL_ERROR "platform cannot be empty")
+  endif()
+  if ("${platform}" MATCHES "^(osx|((ios|watchos|tvos)(sim)?))$")
+    set(is_valid TRUE)
+  endif()
+  set(${is_valid_out} ${is_valid} PARENT_SCOPE)
+endfunction()
+
 set(ARM64 aarch64)
 set(ARM32 arm armhf)
 set(HEXAGON hexagon)
Index: test/asan/CMakeLists.txt
===================================================================
--- test/asan/CMakeLists.txt
+++ test/asan/CMakeLists.txt
@@ -82,15 +82,22 @@
 # variable to select which iOS device or simulator to use, e.g.:
 # SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER="iPhone 6"
 if(APPLE)
+  # FIXME(dliew): This logic should be refactored to the way UBSan Darwin
+  # testing is done.
   set(EXCLUDE_FROM_ALL ON)
 
   set(ASAN_TEST_TARGET_CC ${COMPILER_RT_TEST_COMPILER})
   set(ASAN_TEST_DYNAMIC True)
 
-  foreach(arch ${DARWIN_iossim_ARCHS})
+  list_intersect(ASAN_TEST_IOSSIM_ARCHS ASAN_SUPPORTED_ARCH DARWIN_iossim_ARCHS)
+  foreach(arch ${ASAN_TEST_IOSSIM_ARCHS})
     set(ASAN_TEST_APPLE_PLATFORM "iossim")
     set(ASAN_TEST_TARGET_ARCH ${arch})
-    set(ASAN_TEST_TARGET_CFLAGS "-arch ${arch} -isysroot ${DARWIN_iossim_SYSROOT} ${COMPILER_RT_TEST_COMPILER_CFLAGS}")
+    get_test_cflags_for_apple_platform(
+      "${ASAN_TEST_APPLE_PLATFORM}"
+      "${ASAN_TEST_TARGET_ARCH}"
+      ASAN_TEST_TARGET_CFLAGS
+      )
     set(ASAN_TEST_CONFIG_SUFFIX "-${arch}-${ASAN_TEST_APPLE_PLATFORM}")
     get_bits_for_arch(${arch} ASAN_TEST_BITS)
     string(TOUPPER ${arch} ARCH_UPPER_CASE)
@@ -104,10 +111,14 @@
       DEPENDS ${ASAN_TEST_DEPS})
   endforeach()
 
-  foreach (arch ${DARWIN_ios_ARCHS})
+  list_intersect(ASAN_TEST_IOS_ARCHS ASAN_SUPPORTED_ARCH DARWIN_ios_ARCHS)
+  foreach (arch ${ASAN_TEST_IOS_ARCHS})
     set(ASAN_TEST_APPLE_PLATFORM "ios")
     set(ASAN_TEST_TARGET_ARCH ${arch})
-    set(ASAN_TEST_TARGET_CFLAGS "-arch ${arch} -isysroot ${DARWIN_ios_SYSROOT} ${COMPILER_RT_TEST_COMPILER_CFLAGS}")
+    get_test_cflags_for_apple_platform(
+      "${ASAN_TEST_APPLE_PLATFORM}"
+      "${arch}"
+      ASAN_TEST_TARGET_CFLAGS)
     set(ASAN_TEST_CONFIG_SUFFIX "-${arch}-${ASAN_TEST_APPLE_PLATFORM}")
     get_bits_for_arch(${arch} ASAN_TEST_BITS)
     string(TOUPPER ${arch} ARCH_UPPER_CASE)
Index: test/fuzzer/CMakeLists.txt
===================================================================
--- test/fuzzer/CMakeLists.txt
+++ test/fuzzer/CMakeLists.txt
@@ -89,12 +89,19 @@
 endif()
 
 if (APPLE)
+  # FIXME(dliew): This logic should be refactored to the way UBSan Darwin
+  # testing is done.
   set(EXCLUDE_FROM_ALL ON)
 
-  foreach(arch ${DARWIN_ios_ARCHS})
+  list_intersect(FUZZER_TEST_IOS_ARCHS FUZZER_SUPPORTED_ARCH DARWIN_ios_ARCHS)
+  foreach(arch ${FUZZER_TEST_IOS_ARCHS})
     set(LIBFUZZER_TEST_APPLE_PLATFORM "ios")
     set(LIBFUZZER_TEST_TARGET_ARCH ${arch})
-    set(LIBFUZZER_TEST_FLAGS "-arch ${arch} -isysroot ${DARWIN_ios_SYSROOT} ${COMPILER_RT_TEST_COMPILER_CFLAGS}")
+    get_test_cflags_for_apple_platform(
+      "${LIBFUZZER_TEST_APPLE_PLATFORM}"
+      "${LIBFUZZER_TEST_TARGET_ARCH}"
+      LIBFUZZER_TEST_FLAGS
+      )
     set(LIBFUZZER_TEST_CONFIG_SUFFIX "-${arch}-${LIBFUZZER_TEST_APPLE_PLATFORM}")
     string(TOUPPER ${arch} ARCH_UPPER_CASE)
     set(CONFIG_NAME "IOS${ARCH_UPPER_CASE}Config")
Index: test/tsan/CMakeLists.txt
===================================================================
--- test/tsan/CMakeLists.txt
+++ test/tsan/CMakeLists.txt
@@ -49,39 +49,52 @@
 # variable to select which iOS device or simulator to use, e.g.:
 # SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER="iPhone 6"
 if(APPLE)
+  # FIXME(dliew): This logic should be refactored to the way UBSan Darwin
+  # testing is done.
   set(EXCLUDE_FROM_ALL ON)
-
   set(TSAN_TEST_TARGET_CC ${COMPILER_RT_TEST_COMPILER})
 
-  set(TSAN_TEST_APPLE_PLATFORM "iossim")
-  set(arch "x86_64")
-  set(TSAN_TEST_TARGET_ARCH ${arch})
-  set(TSAN_TEST_TARGET_CFLAGS "-arch ${arch} -isysroot ${DARWIN_iossim_SYSROOT} ${COMPILER_RT_TEST_COMPILER_CFLAGS}")
-  set(TSAN_TEST_CONFIG_SUFFIX "-${arch}-${TSAN_TEST_APPLE_PLATFORM}")
-  string(TOUPPER ${arch} ARCH_UPPER_CASE)
-  set(CONFIG_NAME "IOSSim${ARCH_UPPER_CASE}Config")
-  configure_lit_site_cfg(
-    ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
-    ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg.py
-    )
-  add_lit_testsuite(check-tsan-iossim-${arch} "ThreadSanitizer iOS Simulator ${arch} tests"
-    ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/
-    DEPENDS ${TSAN_TEST_DEPS})
+  list_intersect(TSAN_TEST_IOSSIM_ARCHS TSAN_SUPPORTED_ARCH DARWIN_iossim_ARCHS)
+  foreach(arch ${TSAN_TEST_IOSSIM_ARCHS})
+    set(TSAN_TEST_APPLE_PLATFORM "iossim")
+    set(TSAN_TEST_TARGET_ARCH ${arch})
+    get_test_cflags_for_apple_platform(
+      "${TSAN_TEST_APPLE_PLATFORM}"
+      "${TSAN_TEST_TARGET_ARCH}"
+      TSAN_TEST_TARGET_CFLAGS
+      )
+    set(TSAN_TEST_CONFIG_SUFFIX "-${arch}-${TSAN_TEST_APPLE_PLATFORM}")
+    string(TOUPPER ${arch} ARCH_UPPER_CASE)
+    set(CONFIG_NAME "IOSSim${ARCH_UPPER_CASE}Config")
+    configure_lit_site_cfg(
+      ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
+      ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg.py
+      )
+    add_lit_testsuite(check-tsan-iossim-${arch} "ThreadSanitizer iOS Simulator ${arch} tests"
+      ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/
+      DEPENDS ${TSAN_TEST_DEPS})
+  endforeach()
 
-  set(TSAN_TEST_APPLE_PLATFORM "ios")
-  set(arch "arm64")
-  set(TSAN_TEST_TARGET_ARCH ${arch})
-  set(TSAN_TEST_TARGET_CFLAGS "-arch ${arch} -isysroot ${DARWIN_ios_SYSROOT} ${COMPILER_RT_TEST_COMPILER_CFLAGS}")
-  set(TSAN_TEST_CONFIG_SUFFIX "-${arch}-${TSAN_TEST_APPLE_PLATFORM}")
-  string(TOUPPER ${arch} ARCH_UPPER_CASE)
-  set(CONFIG_NAME "IOS${ARCH_UPPER_CASE}Config")
-  configure_lit_site_cfg(
-    ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
-    ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg.py
-    )
-  add_lit_testsuite(check-tsan-ios-${arch} "ThreadSanitizer iOS Simulator ${arch} tests"
-    ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/
-    DEPENDS ${TSAN_TEST_DEPS})
+  list_intersect(TSAN_TEST_IOS_ARCHS TSAN_SUPPORTED_ARCH DARWIN_ios_ARCHS)
+  foreach(arch ${TSAN_TEST_IOS_ARCHS})
+    set(TSAN_TEST_APPLE_PLATFORM "ios")
+    set(TSAN_TEST_TARGET_ARCH ${arch})
+    get_test_cflags_for_apple_platform(
+      "${TSAN_TEST_APPLE_PLATFORM}"
+      "${TSAN_TEST_TARGET_ARCH}"
+      TSAN_TEST_TARGET_CFLAGS
+      )
+    set(TSAN_TEST_CONFIG_SUFFIX "-${arch}-${TSAN_TEST_APPLE_PLATFORM}")
+    string(TOUPPER ${arch} ARCH_UPPER_CASE)
+    set(CONFIG_NAME "IOS${ARCH_UPPER_CASE}Config")
+    configure_lit_site_cfg(
+      ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
+      ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg.py
+      )
+    add_lit_testsuite(check-tsan-ios-${arch} "ThreadSanitizer iOS ${arch} tests"
+      ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/
+      DEPENDS ${TSAN_TEST_DEPS})
+  endforeach()
 
   set(EXCLUDE_FROM_ALL OFF)
 endif()
Index: test/ubsan/CMakeLists.txt
===================================================================
--- test/ubsan/CMakeLists.txt
+++ test/ubsan/CMakeLists.txt
@@ -101,22 +101,20 @@
   # variable to select which iOS device or simulator to use, e.g.:
   # SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER="iPhone 6"
   set(EXCLUDE_FROM_ALL ON)
-  set(UBSAN_APPLE_PLATFORMS "")
-  if (COMPILER_RT_ENABLE_IOS)
-    list(APPEND UBSAN_APPLE_PLATFORMS ios iossim)
-  endif()
-  if (COMPILER_RT_ENABLE_WATCHOS)
-    list(APPEND UBSAN_APPLE_PLATFORMS watchos watchossim)
-  endif()
-  if (COMPILER_RT_ENABLE_TVOS)
-    list(APPEND UBSAN_APPLE_PLATFORMS tvos tvossim)
-  endif()
+  set(UBSAN_APPLE_PLATFORMS ${SANITIZER_COMMON_SUPPORTED_OS})
   foreach(platform ${UBSAN_APPLE_PLATFORMS})
-    foreach(arch ${DARWIN_${platform}_ARCHS})
-      set(UBSAN_TEST_TARGET_CFLAGS "-arch ${arch} -isysroot ${DARWIN_${platform}_SYSROOT}")
-      if (";${UBSAN_SUPPORTED_ARCH};" MATCHES ";${arch};")
-        add_ubsan_device_testsuite("Standalone" ubsan ${platform} ${arch})
-      endif()
+    list_intersect(
+      UBSAN_TEST_${platform}_ARCHS
+      UBSAN_SUPPORTED_ARCH
+      DARWIN_${platform}_ARCHS
+      )
+    foreach(arch ${UBSAN_TEST_${platform}_ARCHS})
+      get_test_cflags_for_apple_platform(
+        "${platform}"
+        "${arch}"
+        UBSAN_TEST_TARGET_CFLAGS
+      )
+      add_ubsan_device_testsuite("Standalone" ubsan ${platform} ${arch})
 
       if(COMPILER_RT_HAS_ASAN AND ";${ASAN_SUPPORTED_ARCH};" MATCHES ";${arch};")
         add_ubsan_device_testsuite("AddressSanitizer" asan ${platform} ${arch})