diff --git a/infra/bots/recipe_modules/build/chromecast.py b/infra/bots/recipe_modules/build/chromecast.py
index 40e2225a38..4870ba7549 100644
--- a/infra/bots/recipe_modules/build/chromecast.py
+++ b/infra/bots/recipe_modules/build/chromecast.py
@@ -24,6 +24,8 @@ def compile_fn(api, checkout_root, out_dir):
     "-DSK_NO_COMMAND_BUFFER",
     # Avoid unused warning with yyunput
     '-Wno-error=unused-function',
+    # This bot's compiler's doesn't handle try_acquire_capability correctly.
+    '-Wno-thread-safety-analysis',
     # Makes the binary small enough to fit on the small disk.
     '-g0',
     ('-DDUMMY_cast_toolchain_version=%s' %
diff --git a/infra/bots/recipe_modules/build/default.py b/infra/bots/recipe_modules/build/default.py
index 692f0657b9..f57ee281d1 100644
--- a/infra/bots/recipe_modules/build/default.py
+++ b/infra/bots/recipe_modules/build/default.py
@@ -91,6 +91,10 @@ def compile_fn(api, checkout_root, out_dir):
   if os == 'Mac':
     extra_cflags.append(
         '-DDUMMY_xcode_build_version=%s' % XCODE_BUILD_VERSION)
+    if XCODE_CLANG_VERSION.startswith('9.'):
+      # XCode 9 seems to handle try_acquire_capability wrong.
+      extra_cflags.append('-Wno-thread-safety-analysis')
+
     mac_toolchain_cmd = api.vars.slave_dir.join(
         'mac_toolchain', 'mac_toolchain')
     xcode_app_path = api.vars.cache_dir.join('Xcode.app')
diff --git a/infra/bots/recipe_modules/build/examples/full.expected/Build-Debian9-GCC-arm-Release-Chromecast.json b/infra/bots/recipe_modules/build/examples/full.expected/Build-Debian9-GCC-arm-Release-Chromecast.json
index cb86c757f2..7a36769001 100644
--- a/infra/bots/recipe_modules/build/examples/full.expected/Build-Debian9-GCC-arm-Release-Chromecast.json
+++ b/infra/bots/recipe_modules/build/examples/full.expected/Build-Debian9-GCC-arm-Release-Chromecast.json
@@ -32,7 +32,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Debian9-GCC-arm-Release-Chromecast/Release",
-      "--args=ar=\"[START_DIR]/cast_toolchain/armv7a/bin/armv7a-cros-linux-gnueabi-ar\" cc=\"[START_DIR]/cast_toolchain/armv7a/usr/bin/clang-3.9.elf\" cxx=\"[START_DIR]/cast_toolchain/armv7a/usr/bin/clang++-3.9.elf\" extra_asmflags=[\"-target\", \"armv7a-cros-linux-gnueabi\"] extra_cflags=[\"-target\", \"armv7a-cros-linux-gnueabi\", \"--sysroot\", \"[START_DIR]/cast_toolchain/armv7a/usr/armv7a-cros-linux-gnueabi\", \"-I[START_DIR]/chromebook_arm_gles/include\", \"-DMESA_EGL_NO_X11_HEADERS\", \"-DSK_NO_COMMAND_BUFFER\", \"-Wno-error=unused-function\", \"-g0\", \"-DDUMMY_cast_toolchain_version=42\"] extra_ldflags=[\"-target\", \"armv7a-cros-linux-gnueabi\", \"--sysroot\", \"[START_DIR]/cast_toolchain/armv7a/usr/armv7a-cros-linux-gnueabi\", \"-static-libstdc++\", \"-static-libgcc\", \"-L[START_DIR]/cast_toolchain/armv7a/lib\", \"-fuse-ld=gold\", \"-B[START_DIR]/cast_toolchain/armv7a/usr/libexec/gcc\"] is_debug=false skia_enable_gpu=true skia_use_egl=true skia_use_fontconfig=false skia_use_icu=false skia_use_system_freetype2=false target_cpu=\"arm\" werror=true"
+      "--args=ar=\"[START_DIR]/cast_toolchain/armv7a/bin/armv7a-cros-linux-gnueabi-ar\" cc=\"[START_DIR]/cast_toolchain/armv7a/usr/bin/clang-3.9.elf\" cxx=\"[START_DIR]/cast_toolchain/armv7a/usr/bin/clang++-3.9.elf\" extra_asmflags=[\"-target\", \"armv7a-cros-linux-gnueabi\"] extra_cflags=[\"-target\", \"armv7a-cros-linux-gnueabi\", \"--sysroot\", \"[START_DIR]/cast_toolchain/armv7a/usr/armv7a-cros-linux-gnueabi\", \"-I[START_DIR]/chromebook_arm_gles/include\", \"-DMESA_EGL_NO_X11_HEADERS\", \"-DSK_NO_COMMAND_BUFFER\", \"-Wno-error=unused-function\", \"-Wno-thread-safety-analysis\", \"-g0\", \"-DDUMMY_cast_toolchain_version=42\"] extra_ldflags=[\"-target\", \"armv7a-cros-linux-gnueabi\", \"--sysroot\", \"[START_DIR]/cast_toolchain/armv7a/usr/armv7a-cros-linux-gnueabi\", \"-static-libstdc++\", \"-static-libgcc\", \"-L[START_DIR]/cast_toolchain/armv7a/lib\", \"-fuse-ld=gold\", \"-B[START_DIR]/cast_toolchain/armv7a/usr/libexec/gcc\"] is_debug=false skia_enable_gpu=true skia_use_egl=true skia_use_fontconfig=false skia_use_icu=false skia_use_system_freetype2=false target_cpu=\"arm\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {
diff --git a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-arm64-Debug-iOS.json b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-arm64-Debug-iOS.json
index 36706c6c29..14139c01b2 100644
--- a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-arm64-Debug-iOS.json
+++ b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-arm64-Debug-iOS.json
@@ -53,7 +53,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Mac-Clang-arm64-Debug-iOS/Debug",
-      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-O1\"] skia_ios_identity=\".*GS9WA.*\" skia_ios_profile=\"Upstream Testing Provisioning Profile\" target_cpu=\"arm64\" target_os=\"ios\" werror=true"
+      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-Wno-thread-safety-analysis\", \"-O1\"] skia_ios_identity=\".*GS9WA.*\" skia_ios_profile=\"Upstream Testing Provisioning Profile\" target_cpu=\"arm64\" target_os=\"ios\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {
diff --git a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-ASAN.json b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-ASAN.json
index 221d564bb4..e3bc3e6e25 100644
--- a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-ASAN.json
+++ b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-ASAN.json
@@ -53,7 +53,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Mac-Clang-x86_64-Debug-ASAN/Debug",
-      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-O1\"] sanitize=\"ASAN\" skia_enable_spirv_validation=false target_cpu=\"x86_64\" werror=true"
+      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-Wno-thread-safety-analysis\", \"-O1\"] sanitize=\"ASAN\" skia_enable_spirv_validation=false target_cpu=\"x86_64\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {
diff --git a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json
index 3ca3d1f73b..caed31244a 100644
--- a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json
+++ b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json
@@ -74,7 +74,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Mac-Clang-x86_64-Debug-CommandBuffer/Debug",
-      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-O1\"] skia_gl_standard=\"\" target_cpu=\"x86_64\" werror=true"
+      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-Wno-thread-safety-analysis\", \"-O1\"] skia_gl_standard=\"\" target_cpu=\"x86_64\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {
diff --git a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-Metal.json b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-Metal.json
index a25db73a1a..60c6e8fcd5 100644
--- a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-Metal.json
+++ b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Debug-Metal.json
@@ -53,7 +53,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Mac-Clang-x86_64-Debug-Metal/Debug",
-      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-O1\"] skia_use_metal=true target_cpu=\"x86_64\" werror=true"
+      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-Wno-thread-safety-analysis\", \"-O1\"] skia_use_metal=true target_cpu=\"x86_64\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {
diff --git a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Release-MoltenVK_Vulkan.json b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Release-MoltenVK_Vulkan.json
index 2317dba19b..16f83ec6f0 100644
--- a/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Release-MoltenVK_Vulkan.json
+++ b/infra/bots/recipe_modules/build/examples/full.expected/Build-Mac-Clang-x86_64-Release-MoltenVK_Vulkan.json
@@ -53,7 +53,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Mac-Clang-x86_64-Release-MoltenVK_Vulkan/Release",
-      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\"] is_debug=false skia_enable_vulkan_debug_layers=false skia_moltenvk_path=\"[START_DIR]/moltenvk\" skia_use_vulkan=true target_cpu=\"x86_64\" werror=true"
+      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-Wno-thread-safety-analysis\"] is_debug=false skia_enable_vulkan_debug_layers=false skia_moltenvk_path=\"[START_DIR]/moltenvk\" skia_use_vulkan=true target_cpu=\"x86_64\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {
diff --git a/infra/bots/recipes/sync_and_compile.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json b/infra/bots/recipes/sync_and_compile.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json
index d51c0c9c1e..728d5ed9e5 100644
--- a/infra/bots/recipes/sync_and_compile.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json
+++ b/infra/bots/recipes/sync_and_compile.expected/Build-Mac-Clang-x86_64-Debug-CommandBuffer.json
@@ -202,7 +202,7 @@
       "[START_DIR]/cache/work/skia/bin/gn",
       "gen",
       "[START_DIR]/cache/work/skia/out/Build-Mac-Clang-x86_64-Debug-CommandBuffer/Debug",
-      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-O1\"] skia_gl_standard=\"\" target_cpu=\"x86_64\" werror=true"
+      "--args=cc=\"clang\" cxx=\"clang++\" extra_cflags=[\"-DDUMMY_xcode_build_version=9c40b\", \"-Wno-thread-safety-analysis\", \"-O1\"] skia_gl_standard=\"\" target_cpu=\"x86_64\" werror=true"
     ],
     "cwd": "[START_DIR]/cache/work/skia",
     "env": {