diff --git a/composer.json b/composer.json
index 0cafb94808c6887883980495a2f340ee77c158bb..284b57a8098158bed6b57a4d5a473e6fb6021a69 100644
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,7 @@
   "license": "BSD-3-Clause",
   "require": {
     "php": ">=5.5.0",
-    "google/protobuf": "^v3.1.0"
+    "google/protobuf": "^v3.3.0"
   },
   "require-dev": {
     "google/auth": "v0.9"
diff --git a/setup.py b/setup.py
index 18ba802fb0f8762777b128546a5b4156e10b7179..a89511487f1984a9cd20adc3d0ea5ffb183fab83 100644
--- a/setup.py
+++ b/setup.py
@@ -237,7 +237,7 @@ INSTALL_REQUIRES = (
     'six>=1.5.2',
     # TODO(atash): eventually split the grpcio package into a metapackage
     # depending on protobuf and the runtime component (independent of protobuf)
-    'protobuf>=3.2.0',
+    'protobuf>=3.3.0',
 )
 
 if not PY3:
diff --git a/src/php/composer.json b/src/php/composer.json
index 24c17c3b572dacf45772a44005d11a71a09cda1e..a4fba7e4f6a888a963e4ccbc689c02057022fc85 100644
--- a/src/php/composer.json
+++ b/src/php/composer.json
@@ -5,7 +5,7 @@
   "version": "1.4.0",
   "require": {
     "php": ">=5.5.0",
-    "google/protobuf": "^v3.1.0"
+    "google/protobuf": "^v3.3.0"
   },
   "require-dev": {
     "google/auth": "v0.9"
diff --git a/src/python/grpcio_health_checking/setup.py b/src/python/grpcio_health_checking/setup.py
index 1806d311b47658b9a6a3496f78741b00e7c08d6b..f1c09de2eb1f0d6ca474a256e603bec91c922ce6 100644
--- a/src/python/grpcio_health_checking/setup.py
+++ b/src/python/grpcio_health_checking/setup.py
@@ -46,7 +46,7 @@ PACKAGE_DIRECTORIES = {
 SETUP_REQUIRES = (
     'grpcio-tools>={version}'.format(version=grpc_version.VERSION),)
 
-INSTALL_REQUIRES = ('protobuf>=3.2.0',
+INSTALL_REQUIRES = ('protobuf>=3.3.0',
                     'grpcio>={version}'.format(version=grpc_version.VERSION),)
 
 COMMAND_CLASS = {
diff --git a/src/python/grpcio_reflection/setup.py b/src/python/grpcio_reflection/setup.py
index e6cf54745e2d945f492bad31c25f55e215577029..cb49c3d57e7b608542e36f6a4f5950dfae69db78 100644
--- a/src/python/grpcio_reflection/setup.py
+++ b/src/python/grpcio_reflection/setup.py
@@ -47,7 +47,7 @@ PACKAGE_DIRECTORIES = {
 SETUP_REQUIRES = (
     'grpcio-tools>={version}'.format(version=grpc_version.VERSION),)
 
-INSTALL_REQUIRES = ('protobuf>=3.2.0',
+INSTALL_REQUIRES = ('protobuf>=3.3.0',
                     'grpcio>={version}'.format(version=grpc_version.VERSION),)
 
 COMMAND_CLASS = {
diff --git a/src/python/grpcio_tests/setup.py b/src/python/grpcio_tests/setup.py
index b9f0264dae3a29eb025a6bc4ba301b0156e3ef8c..7ee5336a7d6cd07182d2bb8fffecaa3417c72c02 100644
--- a/src/python/grpcio_tests/setup.py
+++ b/src/python/grpcio_tests/setup.py
@@ -56,7 +56,7 @@ INSTALL_REQUIRES = (
     'grpcio>={version}'.format(version=grpc_version.VERSION),
     'grpcio-tools>={version}'.format(version=grpc_version.VERSION),
     'grpcio-health-checking>={version}'.format(version=grpc_version.VERSION),
-    'oauth2client>=1.4.7', 'protobuf>=3.2.0', 'six>=1.10',)
+    'oauth2client>=1.4.7', 'protobuf>=3.3.0', 'six>=1.10',)
 
 COMMAND_CLASS = {
     # Run `preprocess` *before* doing any packaging!
diff --git a/templates/composer.json.template b/templates/composer.json.template
index 94f0c236a9606d43dc5a5b2d02a762fb99215055..2d4cb119195dbb4555cef7d35a67fcf086270739 100644
--- a/templates/composer.json.template
+++ b/templates/composer.json.template
@@ -9,7 +9,7 @@
     "license": "BSD-3-Clause",
     "require": {
       "php": ">=5.5.0",
-      "google/protobuf": "^v3.1.0"
+      "google/protobuf": "^v3.3.0"
     },
     "require-dev": {
       "google/auth": "v0.9"
diff --git a/templates/src/php/composer.json.template b/templates/src/php/composer.json.template
index 1887ee3c822afd08725295d1749b9d5db2257f15..36932cf8f61189404d0b63acd92d6443ce8b8f0e 100644
--- a/templates/src/php/composer.json.template
+++ b/templates/src/php/composer.json.template
@@ -7,7 +7,7 @@
     "version": "${settings.php_version.php_composer()}",
     "require": {
       "php": ">=5.5.0",
-      "google/protobuf": "^v3.1.0"
+      "google/protobuf": "^v3.3.0"
     },
     "require-dev": {
       "google/auth": "v0.9"
diff --git a/third_party/protobuf b/third_party/protobuf
index 593e917c176b5bc5aafa57bf9f6030d749d91cd5..a6189acd18b00611c1dc7042299ad75486f08a1a 160000
--- a/third_party/protobuf
+++ b/third_party/protobuf
@@ -1 +1 @@
-Subproject commit 593e917c176b5bc5aafa57bf9f6030d749d91cd5
+Subproject commit a6189acd18b00611c1dc7042299ad75486f08a1a
diff --git a/tools/distrib/python/grpcio_tools/protoc_lib_deps.py b/tools/distrib/python/grpcio_tools/protoc_lib_deps.py
index c2aa6198b3d7c442548f2f1c4fa9dd5c18a76e63..8a251f876ab9a609023713afef8ae494d016f501 100644
--- a/tools/distrib/python/grpcio_tools/protoc_lib_deps.py
+++ b/tools/distrib/python/grpcio_tools/protoc_lib_deps.py
@@ -29,8 +29,8 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 # AUTO-GENERATED BY make_grpcio_tools.py!
-CC_FILES=['google/protobuf/compiler/zip_writer.cc', 'google/protobuf/compiler/subprocess.cc', 'google/protobuf/compiler/ruby/ruby_generator.cc', 'google/protobuf/compiler/python/python_generator.cc', 'google/protobuf/compiler/plugin.pb.cc', 'google/protobuf/compiler/plugin.cc', 'google/protobuf/compiler/php/php_generator.cc', 'google/protobuf/compiler/objectivec/objectivec_primitive_field.cc', 'google/protobuf/compiler/objectivec/objectivec_oneof.cc', 'google/protobuf/compiler/objectivec/objectivec_message_field.cc', 'google/protobuf/compiler/objectivec/objectivec_message.cc', 'google/protobuf/compiler/objectivec/objectivec_map_field.cc', 'google/protobuf/compiler/objectivec/objectivec_helpers.cc', 'google/protobuf/compiler/objectivec/objectivec_generator.cc', 'google/protobuf/compiler/objectivec/objectivec_file.cc', 'google/protobuf/compiler/objectivec/objectivec_field.cc', 'google/protobuf/compiler/objectivec/objectivec_extension.cc', 'google/protobuf/compiler/objectivec/objectivec_enum_field.cc', 'google/protobuf/compiler/objectivec/objectivec_enum.cc', 'google/protobuf/compiler/js/well_known_types_embed.cc', 'google/protobuf/compiler/js/js_generator.cc', 'google/protobuf/compiler/javanano/javanano_primitive_field.cc', 'google/protobuf/compiler/javanano/javanano_message_field.cc', 'google/protobuf/compiler/javanano/javanano_message.cc', 'google/protobuf/compiler/javanano/javanano_map_field.cc', 'google/protobuf/compiler/javanano/javanano_helpers.cc', 'google/protobuf/compiler/javanano/javanano_generator.cc', 'google/protobuf/compiler/javanano/javanano_file.cc', 'google/protobuf/compiler/javanano/javanano_field.cc', 'google/protobuf/compiler/javanano/javanano_extension.cc', 'google/protobuf/compiler/javanano/javanano_enum_field.cc', 'google/protobuf/compiler/javanano/javanano_enum.cc', 'google/protobuf/compiler/java/java_string_field_lite.cc', 'google/protobuf/compiler/java/java_string_field.cc', 'google/protobuf/compiler/java/java_shared_code_generator.cc', 'google/protobuf/compiler/java/java_service.cc', 'google/protobuf/compiler/java/java_primitive_field_lite.cc', 'google/protobuf/compiler/java/java_primitive_field.cc', 'google/protobuf/compiler/java/java_name_resolver.cc', 'google/protobuf/compiler/java/java_message_lite.cc', 'google/protobuf/compiler/java/java_message_field_lite.cc', 'google/protobuf/compiler/java/java_message_field.cc', 'google/protobuf/compiler/java/java_message_builder_lite.cc', 'google/protobuf/compiler/java/java_message_builder.cc', 'google/protobuf/compiler/java/java_message.cc', 'google/protobuf/compiler/java/java_map_field_lite.cc', 'google/protobuf/compiler/java/java_map_field.cc', 'google/protobuf/compiler/java/java_lazy_message_field_lite.cc', 'google/protobuf/compiler/java/java_lazy_message_field.cc', 'google/protobuf/compiler/java/java_helpers.cc', 'google/protobuf/compiler/java/java_generator_factory.cc', 'google/protobuf/compiler/java/java_generator.cc', 'google/protobuf/compiler/java/java_file.cc', 'google/protobuf/compiler/java/java_field.cc', 'google/protobuf/compiler/java/java_extension_lite.cc', 'google/protobuf/compiler/java/java_extension.cc', 'google/protobuf/compiler/java/java_enum_lite.cc', 'google/protobuf/compiler/java/java_enum_field_lite.cc', 'google/protobuf/compiler/java/java_enum_field.cc', 'google/protobuf/compiler/java/java_enum.cc', 'google/protobuf/compiler/java/java_doc_comment.cc', 'google/protobuf/compiler/java/java_context.cc', 'google/protobuf/compiler/csharp/csharp_wrapper_field.cc', 'google/protobuf/compiler/csharp/csharp_source_generator_base.cc', 'google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc', 'google/protobuf/compiler/csharp/csharp_repeated_message_field.cc', 'google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc', 'google/protobuf/compiler/csharp/csharp_reflection_class.cc', 'google/protobuf/compiler/csharp/csharp_primitive_field.cc', 'google/protobuf/compiler/csharp/csharp_message_field.cc', 'google/protobuf/compiler/csharp/csharp_message.cc', 'google/protobuf/compiler/csharp/csharp_map_field.cc', 'google/protobuf/compiler/csharp/csharp_helpers.cc', 'google/protobuf/compiler/csharp/csharp_generator.cc', 'google/protobuf/compiler/csharp/csharp_field_base.cc', 'google/protobuf/compiler/csharp/csharp_enum_field.cc', 'google/protobuf/compiler/csharp/csharp_enum.cc', 'google/protobuf/compiler/csharp/csharp_doc_comment.cc', 'google/protobuf/compiler/cpp/cpp_string_field.cc', 'google/protobuf/compiler/cpp/cpp_service.cc', 'google/protobuf/compiler/cpp/cpp_primitive_field.cc', 'google/protobuf/compiler/cpp/cpp_message_field.cc', 'google/protobuf/compiler/cpp/cpp_message.cc', 'google/protobuf/compiler/cpp/cpp_map_field.cc', 'google/protobuf/compiler/cpp/cpp_helpers.cc', 'google/protobuf/compiler/cpp/cpp_generator.cc', 'google/protobuf/compiler/cpp/cpp_file.cc', 'google/protobuf/compiler/cpp/cpp_field.cc', 'google/protobuf/compiler/cpp/cpp_extension.cc', 'google/protobuf/compiler/cpp/cpp_enum_field.cc', 'google/protobuf/compiler/cpp/cpp_enum.cc', 'google/protobuf/compiler/command_line_interface.cc', 'google/protobuf/compiler/code_generator.cc', 'google/protobuf/wrappers.pb.cc', 'google/protobuf/wire_format.cc', 'google/protobuf/util/type_resolver_util.cc', 'google/protobuf/util/time_util.cc', 'google/protobuf/util/message_differencer.cc', 'google/protobuf/util/json_util.cc', 'google/protobuf/util/internal/utility.cc', 'google/protobuf/util/internal/type_info_test_helper.cc', 'google/protobuf/util/internal/type_info.cc', 'google/protobuf/util/internal/protostream_objectwriter.cc', 'google/protobuf/util/internal/protostream_objectsource.cc', 'google/protobuf/util/internal/proto_writer.cc', 'google/protobuf/util/internal/object_writer.cc', 'google/protobuf/util/internal/json_stream_parser.cc', 'google/protobuf/util/internal/json_objectwriter.cc', 'google/protobuf/util/internal/json_escaping.cc', 'google/protobuf/util/internal/field_mask_utility.cc', 'google/protobuf/util/internal/error_listener.cc', 'google/protobuf/util/internal/default_value_objectwriter.cc', 'google/protobuf/util/internal/datapiece.cc', 'google/protobuf/util/field_mask_util.cc', 'google/protobuf/util/field_comparator.cc', 'google/protobuf/unknown_field_set.cc', 'google/protobuf/type.pb.cc', 'google/protobuf/timestamp.pb.cc', 'google/protobuf/text_format.cc', 'google/protobuf/stubs/substitute.cc', 'google/protobuf/stubs/mathlimits.cc', 'google/protobuf/struct.pb.cc', 'google/protobuf/source_context.pb.cc', 'google/protobuf/service.cc', 'google/protobuf/reflection_ops.cc', 'google/protobuf/message.cc', 'google/protobuf/map_field.cc', 'google/protobuf/io/zero_copy_stream_impl.cc', 'google/protobuf/io/tokenizer.cc', 'google/protobuf/io/strtod.cc', 'google/protobuf/io/printer.cc', 'google/protobuf/io/gzip_stream.cc', 'google/protobuf/generated_message_reflection.cc', 'google/protobuf/field_mask.pb.cc', 'google/protobuf/extension_set_heavy.cc', 'google/protobuf/empty.pb.cc', 'google/protobuf/dynamic_message.cc', 'google/protobuf/duration.pb.cc', 'google/protobuf/descriptor_database.cc', 'google/protobuf/descriptor.pb.cc', 'google/protobuf/descriptor.cc', 'google/protobuf/compiler/parser.cc', 'google/protobuf/compiler/importer.cc', 'google/protobuf/api.pb.cc', 'google/protobuf/any.pb.cc', 'google/protobuf/any.cc', 'google/protobuf/wire_format_lite.cc', 'google/protobuf/stubs/time.cc', 'google/protobuf/stubs/strutil.cc', 'google/protobuf/stubs/structurally_valid.cc', 'google/protobuf/stubs/stringprintf.cc', 'google/protobuf/stubs/stringpiece.cc', 'google/protobuf/stubs/statusor.cc', 'google/protobuf/stubs/status.cc', 'google/protobuf/stubs/once.cc', 'google/protobuf/stubs/int128.cc', 'google/protobuf/stubs/common.cc', 'google/protobuf/stubs/bytestream.cc', 'google/protobuf/stubs/atomicops_internals_x86_msvc.cc', 'google/protobuf/stubs/atomicops_internals_x86_gcc.cc', 'google/protobuf/repeated_field.cc', 'google/protobuf/message_lite.cc', 'google/protobuf/io/zero_copy_stream_impl_lite.cc', 'google/protobuf/io/zero_copy_stream.cc', 'google/protobuf/io/coded_stream.cc', 'google/protobuf/generated_message_util.cc', 'google/protobuf/extension_set.cc', 'google/protobuf/arenastring.cc', 'google/protobuf/arena.cc', 'google/protobuf/compiler/js/embed.cc']
-PROTO_FILES=['google/protobuf/wrappers.proto', 'google/protobuf/type.proto', 'google/protobuf/timestamp.proto', 'google/protobuf/struct.proto', 'google/protobuf/source_context.proto', 'google/protobuf/field_mask.proto', 'google/protobuf/empty.proto', 'google/protobuf/duration.proto', 'google/protobuf/descriptor.proto', 'google/protobuf/compiler/plugin.proto', 'google/protobuf/api.proto', 'google/protobuf/any.proto']
+CC_FILES=['google/protobuf/compiler/zip_writer.cc', 'google/protobuf/compiler/subprocess.cc', 'google/protobuf/compiler/ruby/ruby_generator.cc', 'google/protobuf/compiler/python/python_generator.cc', 'google/protobuf/compiler/profile.pb.cc', 'google/protobuf/compiler/plugin.pb.cc', 'google/protobuf/compiler/plugin.cc', 'google/protobuf/compiler/php/php_generator.cc', 'google/protobuf/compiler/objectivec/objectivec_primitive_field.cc', 'google/protobuf/compiler/objectivec/objectivec_oneof.cc', 'google/protobuf/compiler/objectivec/objectivec_message_field.cc', 'google/protobuf/compiler/objectivec/objectivec_message.cc', 'google/protobuf/compiler/objectivec/objectivec_map_field.cc', 'google/protobuf/compiler/objectivec/objectivec_helpers.cc', 'google/protobuf/compiler/objectivec/objectivec_generator.cc', 'google/protobuf/compiler/objectivec/objectivec_file.cc', 'google/protobuf/compiler/objectivec/objectivec_field.cc', 'google/protobuf/compiler/objectivec/objectivec_extension.cc', 'google/protobuf/compiler/objectivec/objectivec_enum_field.cc', 'google/protobuf/compiler/objectivec/objectivec_enum.cc', 'google/protobuf/compiler/js/well_known_types_embed.cc', 'google/protobuf/compiler/js/js_generator.cc', 'google/protobuf/compiler/javanano/javanano_primitive_field.cc', 'google/protobuf/compiler/javanano/javanano_message_field.cc', 'google/protobuf/compiler/javanano/javanano_message.cc', 'google/protobuf/compiler/javanano/javanano_map_field.cc', 'google/protobuf/compiler/javanano/javanano_helpers.cc', 'google/protobuf/compiler/javanano/javanano_generator.cc', 'google/protobuf/compiler/javanano/javanano_file.cc', 'google/protobuf/compiler/javanano/javanano_field.cc', 'google/protobuf/compiler/javanano/javanano_extension.cc', 'google/protobuf/compiler/javanano/javanano_enum_field.cc', 'google/protobuf/compiler/javanano/javanano_enum.cc', 'google/protobuf/compiler/java/java_string_field_lite.cc', 'google/protobuf/compiler/java/java_string_field.cc', 'google/protobuf/compiler/java/java_shared_code_generator.cc', 'google/protobuf/compiler/java/java_service.cc', 'google/protobuf/compiler/java/java_primitive_field_lite.cc', 'google/protobuf/compiler/java/java_primitive_field.cc', 'google/protobuf/compiler/java/java_name_resolver.cc', 'google/protobuf/compiler/java/java_message_lite.cc', 'google/protobuf/compiler/java/java_message_field_lite.cc', 'google/protobuf/compiler/java/java_message_field.cc', 'google/protobuf/compiler/java/java_message_builder_lite.cc', 'google/protobuf/compiler/java/java_message_builder.cc', 'google/protobuf/compiler/java/java_message.cc', 'google/protobuf/compiler/java/java_map_field_lite.cc', 'google/protobuf/compiler/java/java_map_field.cc', 'google/protobuf/compiler/java/java_lazy_message_field_lite.cc', 'google/protobuf/compiler/java/java_lazy_message_field.cc', 'google/protobuf/compiler/java/java_helpers.cc', 'google/protobuf/compiler/java/java_generator_factory.cc', 'google/protobuf/compiler/java/java_generator.cc', 'google/protobuf/compiler/java/java_file.cc', 'google/protobuf/compiler/java/java_field.cc', 'google/protobuf/compiler/java/java_extension_lite.cc', 'google/protobuf/compiler/java/java_extension.cc', 'google/protobuf/compiler/java/java_enum_lite.cc', 'google/protobuf/compiler/java/java_enum_field_lite.cc', 'google/protobuf/compiler/java/java_enum_field.cc', 'google/protobuf/compiler/java/java_enum.cc', 'google/protobuf/compiler/java/java_doc_comment.cc', 'google/protobuf/compiler/java/java_context.cc', 'google/protobuf/compiler/csharp/csharp_wrapper_field.cc', 'google/protobuf/compiler/csharp/csharp_source_generator_base.cc', 'google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc', 'google/protobuf/compiler/csharp/csharp_repeated_message_field.cc', 'google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc', 'google/protobuf/compiler/csharp/csharp_reflection_class.cc', 'google/protobuf/compiler/csharp/csharp_primitive_field.cc', 'google/protobuf/compiler/csharp/csharp_message_field.cc', 'google/protobuf/compiler/csharp/csharp_message.cc', 'google/protobuf/compiler/csharp/csharp_map_field.cc', 'google/protobuf/compiler/csharp/csharp_helpers.cc', 'google/protobuf/compiler/csharp/csharp_generator.cc', 'google/protobuf/compiler/csharp/csharp_field_base.cc', 'google/protobuf/compiler/csharp/csharp_enum_field.cc', 'google/protobuf/compiler/csharp/csharp_enum.cc', 'google/protobuf/compiler/csharp/csharp_doc_comment.cc', 'google/protobuf/compiler/cpp/cpp_string_field.cc', 'google/protobuf/compiler/cpp/cpp_service.cc', 'google/protobuf/compiler/cpp/cpp_primitive_field.cc', 'google/protobuf/compiler/cpp/cpp_message_field.cc', 'google/protobuf/compiler/cpp/cpp_message.cc', 'google/protobuf/compiler/cpp/cpp_map_field.cc', 'google/protobuf/compiler/cpp/cpp_helpers.cc', 'google/protobuf/compiler/cpp/cpp_generator.cc', 'google/protobuf/compiler/cpp/cpp_file.cc', 'google/protobuf/compiler/cpp/cpp_field.cc', 'google/protobuf/compiler/cpp/cpp_extension.cc', 'google/protobuf/compiler/cpp/cpp_enum_field.cc', 'google/protobuf/compiler/cpp/cpp_enum.cc', 'google/protobuf/compiler/command_line_interface.cc', 'google/protobuf/compiler/code_generator.cc', 'google/protobuf/wrappers.pb.cc', 'google/protobuf/wire_format.cc', 'google/protobuf/util/type_resolver_util.cc', 'google/protobuf/util/time_util.cc', 'google/protobuf/util/message_differencer.cc', 'google/protobuf/util/json_util.cc', 'google/protobuf/util/internal/utility.cc', 'google/protobuf/util/internal/type_info_test_helper.cc', 'google/protobuf/util/internal/type_info.cc', 'google/protobuf/util/internal/protostream_objectwriter.cc', 'google/protobuf/util/internal/protostream_objectsource.cc', 'google/protobuf/util/internal/proto_writer.cc', 'google/protobuf/util/internal/object_writer.cc', 'google/protobuf/util/internal/json_stream_parser.cc', 'google/protobuf/util/internal/json_objectwriter.cc', 'google/protobuf/util/internal/json_escaping.cc', 'google/protobuf/util/internal/field_mask_utility.cc', 'google/protobuf/util/internal/error_listener.cc', 'google/protobuf/util/internal/default_value_objectwriter.cc', 'google/protobuf/util/internal/datapiece.cc', 'google/protobuf/util/field_mask_util.cc', 'google/protobuf/util/field_comparator.cc', 'google/protobuf/util/delimited_message_util.cc', 'google/protobuf/unknown_field_set.cc', 'google/protobuf/type.pb.cc', 'google/protobuf/timestamp.pb.cc', 'google/protobuf/text_format.cc', 'google/protobuf/stubs/substitute.cc', 'google/protobuf/stubs/mathlimits.cc', 'google/protobuf/struct.pb.cc', 'google/protobuf/source_context.pb.cc', 'google/protobuf/service.cc', 'google/protobuf/reflection_ops.cc', 'google/protobuf/message.cc', 'google/protobuf/map_field.cc', 'google/protobuf/io/zero_copy_stream_impl.cc', 'google/protobuf/io/tokenizer.cc', 'google/protobuf/io/strtod.cc', 'google/protobuf/io/printer.cc', 'google/protobuf/io/gzip_stream.cc', 'google/protobuf/generated_message_reflection.cc', 'google/protobuf/field_mask.pb.cc', 'google/protobuf/extension_set_heavy.cc', 'google/protobuf/empty.pb.cc', 'google/protobuf/dynamic_message.cc', 'google/protobuf/duration.pb.cc', 'google/protobuf/descriptor_database.cc', 'google/protobuf/descriptor.pb.cc', 'google/protobuf/descriptor.cc', 'google/protobuf/compiler/parser.cc', 'google/protobuf/compiler/importer.cc', 'google/protobuf/api.pb.cc', 'google/protobuf/any.pb.cc', 'google/protobuf/any.cc', 'google/protobuf/wire_format_lite.cc', 'google/protobuf/stubs/time.cc', 'google/protobuf/stubs/strutil.cc', 'google/protobuf/stubs/structurally_valid.cc', 'google/protobuf/stubs/stringprintf.cc', 'google/protobuf/stubs/stringpiece.cc', 'google/protobuf/stubs/statusor.cc', 'google/protobuf/stubs/status.cc', 'google/protobuf/stubs/once.cc', 'google/protobuf/stubs/int128.cc', 'google/protobuf/stubs/common.cc', 'google/protobuf/stubs/bytestream.cc', 'google/protobuf/stubs/atomicops_internals_x86_msvc.cc', 'google/protobuf/stubs/atomicops_internals_x86_gcc.cc', 'google/protobuf/repeated_field.cc', 'google/protobuf/message_lite.cc', 'google/protobuf/io/zero_copy_stream_impl_lite.cc', 'google/protobuf/io/zero_copy_stream.cc', 'google/protobuf/io/coded_stream.cc', 'google/protobuf/generated_message_util.cc', 'google/protobuf/extension_set.cc', 'google/protobuf/arenastring.cc', 'google/protobuf/arena.cc', 'google/protobuf/compiler/js/embed.cc']
+PROTO_FILES=['google/protobuf/wrappers.proto', 'google/protobuf/type.proto', 'google/protobuf/timestamp.proto', 'google/protobuf/struct.proto', 'google/protobuf/source_context.proto', 'google/protobuf/field_mask.proto', 'google/protobuf/empty.proto', 'google/protobuf/duration.proto', 'google/protobuf/descriptor.proto', 'google/protobuf/compiler/profile.proto', 'google/protobuf/compiler/plugin.proto', 'google/protobuf/api.proto', 'google/protobuf/any.proto']
 
 CC_INCLUDE='third_party/protobuf/src'
 PROTO_INCLUDE='third_party/protobuf/src'
diff --git a/tools/distrib/python/grpcio_tools/setup.py b/tools/distrib/python/grpcio_tools/setup.py
index 211d442f1767462adf0f3c6d616812c2d3a83408..43b60b142f3f747450fd62059413d0726dd9d507 100644
--- a/tools/distrib/python/grpcio_tools/setup.py
+++ b/tools/distrib/python/grpcio_tools/setup.py
@@ -211,7 +211,7 @@ setuptools.setup(
   ext_modules=extension_modules(),
   packages=setuptools.find_packages('.'),
   install_requires=[
-    'protobuf>=3.2.0',
+    'protobuf>=3.3.0',
     'grpcio>={version}'.format(version=grpc_version.VERSION),
   ],
   package_data=package_data(),
diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index 474b56b5de5f6dc5735226ab4285ae6dce2fa04f..76e83ef22fa35241f3b309dd4b590d76ca06229e 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -208,7 +208,7 @@ def _create_portability_test_jobs(extra_args=[], inner_jobs=_DEFAULT_INNER_JOBS)
                                 extra_args=extra_args,
                                 inner_jobs=inner_jobs)
 
-  for compiler in ['gcc4.8', 'gcc5.3',
+  for compiler in ['gcc4.8', 'gcc5.3', 'gcc_musl',
                    'clang3.5', 'clang3.6', 'clang3.7']:
     test_jobs += _generate_jobs(languages=['c++'],
                                 configs=['dbg'],
@@ -267,6 +267,15 @@ def _create_portability_test_jobs(extra_args=[], inner_jobs=_DEFAULT_INNER_JOBS)
                               extra_args=extra_args,
                               inner_jobs=inner_jobs)
 
+  test_jobs += _generate_jobs(languages=['python'],
+                              configs=['dbg'],
+                              platforms=['linux'],
+                              arch='default',
+                              compiler='python_alpine',
+                              labels=['portability'],
+                              extra_args=extra_args,
+                              inner_jobs=inner_jobs)
+
   test_jobs += _generate_jobs(languages=['csharp'],
                               configs=['dbg'],
                               platforms=['linux'],
diff --git a/tools/run_tests/sanity/check_submodules.sh b/tools/run_tests/sanity/check_submodules.sh
index 6be7a39d070f62fc459f55cfb7922b45938ccdc3..43d05212e875cae0177cb207443361b7c3526d07 100755
--- a/tools/run_tests/sanity/check_submodules.sh
+++ b/tools/run_tests/sanity/check_submodules.sh
@@ -46,7 +46,7 @@ cat << EOF | awk '{ print $1 }' | sort > $want_submodules
  886e7d75368e3f4fab3f4d0d3584e4abfc557755 third_party/boringssl-with-bazel (version_for_cocoapods_7.0-857-g886e7d7)
  30dbc81fb5ffdc98ea9b14b1918bfe4e8779b26e third_party/gflags (v2.2.0)
  ec44c6c1675c25b9827aacd08c02433cccde7780 third_party/googletest (release-1.8.0)
- 593e917c176b5bc5aafa57bf9f6030d749d91cd5 third_party/protobuf (v3.1.0-alpha-1-326-g593e917)
+ a6189acd18b00611c1dc7042299ad75486f08a1a third_party/protobuf (v3.3.0)
  cacf7f1d4e3d44d871b605da3b647f07d718623f third_party/zlib (v1.2.11)
  7691f773af79bf75a62d1863fd0f13ebf9dc51b1 third_party/cares/cares (1.12.0)
 EOF