diff -Naur a/Makefile b/Makefile
--- a/Makefile	2017-03-02 10:19:16.000000000 -0800
+++ b/Makefile	2017-03-20 17:15:24.215639798 -0700
@@ -258,6 +258,7 @@
 prefix ?= /usr/local
 
 PROTOC ?= protoc
+PROTOBUF_SRC_DIR ?= third_party/protobuf/src
 DTRACE ?= dtrace
 CONFIG ?= opt
 # Doing X ?= Y is the same as:
@@ -765,7 +766,7 @@
 CPPFLAGS := -Ithird_party/googletest/include $(CPPFLAGS)
 
 PROTOC_PLUGINS_ALL = $(BINDIR)/$(CONFIG)/grpc_cpp_plugin $(BINDIR)/$(CONFIG)/grpc_csharp_plugin $(BINDIR)/$(CONFIG)/grpc_node_plugin $(BINDIR)/$(CONFIG)/grpc_objective_c_plugin $(BINDIR)/$(CONFIG)/grpc_php_plugin $(BINDIR)/$(CONFIG)/grpc_python_plugin $(BINDIR)/$(CONFIG)/grpc_ruby_plugin
-PROTOC_PLUGINS_DIR = $(BINDIR)/$(CONFIG)
+PROTOC_PLUGINS_DIR ?= $(BINDIR)/$(CONFIG)
 
 ifeq ($(HAS_SYSTEM_PROTOBUF),true)
 ifeq ($(HAS_PKG_CONFIG),true)
@@ -778,6 +779,7 @@
 LDFLAGS_PROTOBUF_PKG_CONFIG += $(shell $(PKG_CONFIG) --libs-only-L protobuf | sed s/L/Wl,-rpath,/)
 endif
 endif
+LDFLAGS += $(LDFLAGS_PROTOBUF_PKG_CONFIG)
 else
 PC_LIBS_GRPCXX = -lprotobuf
 endif
@@ -2087,12 +2089,12 @@
 $(GENDIR)/src/proto/grpc/lb/v1/load_balancer.pb.cc: src/proto/grpc/lb/v1/load_balancer.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/lb/v1/load_balancer.grpc.pb.cc: src/proto/grpc/lb/v1/load_balancer.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2102,12 +2104,12 @@
 $(GENDIR)/src/proto/grpc/reflection/v1alpha/reflection.pb.cc: src/proto/grpc/reflection/v1alpha/reflection.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/reflection/v1alpha/reflection.grpc.pb.cc: src/proto/grpc/reflection/v1alpha/reflection.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2117,12 +2119,12 @@
 $(GENDIR)/src/proto/grpc/testing/compiler_test.pb.cc: src/proto/grpc/testing/compiler_test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/compiler_test.grpc.pb.cc: src/proto/grpc/testing/compiler_test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2132,12 +2134,12 @@
 $(GENDIR)/src/proto/grpc/testing/control.pb.cc: src/proto/grpc/testing/control.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/control.grpc.pb.cc: src/proto/grpc/testing/control.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2147,12 +2149,12 @@
 $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc: src/proto/grpc/testing/duplicate/echo_duplicate.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc: src/proto/grpc/testing/duplicate/echo_duplicate.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2162,12 +2164,12 @@
 $(GENDIR)/src/proto/grpc/testing/echo.pb.cc: src/proto/grpc/testing/echo.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc: src/proto/grpc/testing/echo.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2177,12 +2179,12 @@
 $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc: src/proto/grpc/testing/echo_messages.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc: src/proto/grpc/testing/echo_messages.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2192,12 +2194,12 @@
 $(GENDIR)/src/proto/grpc/testing/empty.pb.cc: src/proto/grpc/testing/empty.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/empty.grpc.pb.cc: src/proto/grpc/testing/empty.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2207,12 +2209,12 @@
 $(GENDIR)/src/proto/grpc/testing/messages.pb.cc: src/proto/grpc/testing/messages.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc: src/proto/grpc/testing/messages.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2222,12 +2224,12 @@
 $(GENDIR)/src/proto/grpc/testing/metrics.pb.cc: src/proto/grpc/testing/metrics.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/metrics.grpc.pb.cc: src/proto/grpc/testing/metrics.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2237,12 +2239,12 @@
 $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc: src/proto/grpc/testing/payloads.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/payloads.grpc.pb.cc: src/proto/grpc/testing/payloads.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2252,12 +2254,12 @@
 $(GENDIR)/src/proto/grpc/testing/services.pb.cc: src/proto/grpc/testing/services.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/control.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/services.grpc.pb.cc: src/proto/grpc/testing/services.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/control.pb.cc $(GENDIR)/src/proto/grpc/testing/control.grpc.pb.cc
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2267,12 +2269,12 @@
 $(GENDIR)/src/proto/grpc/testing/stats.pb.cc: src/proto/grpc/testing/stats.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc: src/proto/grpc/testing/stats.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
@@ -2282,12 +2284,12 @@
 $(GENDIR)/src/proto/grpc/testing/test.pb.cc: src/proto/grpc/testing/test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/empty.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --cpp_out=$(GENDIR) $<
 
 $(GENDIR)/src/proto/grpc/testing/test.grpc.pb.cc: src/proto/grpc/testing/test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/empty.pb.cc $(GENDIR)/src/proto/grpc/testing/empty.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -I$(PROTOBUF_SRC_DIR) -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif