diff --git a/CMakeLists.txt b/CMakeLists.txt
index a89efb493d0..6ce00ecacdf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -100,14 +100,16 @@ if (MSVC)
   include(cmake/msvc_static_runtime.cmake)
   add_definitions(-D_WIN32_WINNT=0x600 -D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS -D_WINSOCK_DEPRECATED_NO_WARNINGS)
   # needed to compile protobuf
-  add_definitions(/wd4065 /wd4506)
+  set(_gRPC_C_CXX_FLAGS "${_gRPC_C_CXX_FLAGS} /wd4065 /wd4506")
   # TODO(jtattermusch): revisit warnings that were silenced as part of upgrade to protobuf3.6.0
-  add_definitions(/wd4200 /wd4291 /wd4244)
+  set(_gRPC_C_CXX_FLAGS "${_gRPC_C_CXX_FLAGS} /wd4200 /wd4291 /wd4244")
   # TODO(jtattermusch): revisit C4267 occurrences throughout the code
-  add_definitions(/wd4267)
+  set(_gRPC_C_CXX_FLAGS "${_gRPC_C_CXX_FLAGS} /wd4267")
   # TODO(jtattermusch): needed to build boringssl with VS2017, revisit later
-  add_definitions(/wd4987 /wd4774 /wd4819 /wd4996 /wd4619)
+  set(_gRPC_C_CXX_FLAGS "${_gRPC_C_CXX_FLAGS} /wd4987 /wd4774 /wd4819 /wd4996 /wd4619")
 endif()
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${_gRPC_C_CXX_FLAGS}")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_gRPC_C_CXX_FLAGS}")
 
 if (gRPC_USE_PROTO_LITE)
   set(_gRPC_PROTOBUF_LIBRARY_NAME "libprotobuf-lite")
diff --git a/templates/CMakeLists.txt.template b/templates/CMakeLists.txt.template
index 16fc78d99ae..77769cb93bf 100644
--- a/templates/CMakeLists.txt.template
+++ b/templates/CMakeLists.txt.template
@@ -149,14 +149,16 @@
     include(cmake/msvc_static_runtime.cmake)
     add_definitions(-D_WIN32_WINNT=0x600 -D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS -D_WINSOCK_DEPRECATED_NO_WARNINGS)
     # needed to compile protobuf
-    add_definitions(/wd4065 /wd4506)
+    set(_gRPC_C_CXX_FLAGS "<%text>${_gRPC_C_CXX_FLAGS}</%text> /wd4065 /wd4506")
     # TODO(jtattermusch): revisit warnings that were silenced as part of upgrade to protobuf3.6.0
-    add_definitions(/wd4200 /wd4291 /wd4244)
+    set(_gRPC_C_CXX_FLAGS "<%text>${_gRPC_C_CXX_FLAGS}</%text> /wd4200 /wd4291 /wd4244")
     # TODO(jtattermusch): revisit C4267 occurrences throughout the code
-    add_definitions(/wd4267)
+    set(_gRPC_C_CXX_FLAGS "<%text>${_gRPC_C_CXX_FLAGS}</%text> /wd4267")
     # TODO(jtattermusch): needed to build boringssl with VS2017, revisit later
-    add_definitions(/wd4987 /wd4774 /wd4819 /wd4996 /wd4619)
+    set(_gRPC_C_CXX_FLAGS "<%text>${_gRPC_C_CXX_FLAGS}</%text> /wd4987 /wd4774 /wd4819 /wd4996 /wd4619")
   endif()
+  set(CMAKE_C_FLAGS "<%text>${CMAKE_C_FLAGS} ${_gRPC_C_CXX_FLAGS}</%text>")
+  set(CMAKE_CXX_FLAGS "<%text>${CMAKE_CXX_FLAGS} ${_gRPC_C_CXX_FLAGS}</%text>")
 
   if (gRPC_USE_PROTO_LITE)
     set(_gRPC_PROTOBUF_LIBRARY_NAME "libprotobuf-lite")