diff --git a/.gitignore b/.gitignore
index e097bab3..a965a99b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@ compile_commands.json
 /external/spirv-headers
 /external/effcee
 /external/re2
+/external/protobuf
 /out
 /TAGS
 /third_party/llvm-build/
diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index d1251c24..3190f4b0 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -102,3 +102,15 @@ if (NOT ${SPIRV_SKIP_TESTS})
     endif()
   endif()
 endif()
+
+if(SPIRV_BUILD_FUZZER)
+  set(PROTOBUF_DIR ${CMAKE_CURRENT_SOURCE_DIR}/protobuf/cmake)
+  set(protobuf_BUILD_TESTS OFF CACHE BOOL "Disable protobuf tests")
+  set(protobuf_MSVC_STATIC_RUNTIME OFF CACHE BOOL "Do not build protobuf static runtime")
+  if (IS_DIRECTORY ${PROTOBUF_DIR})
+    add_subdirectory(${PROTOBUF_DIR} EXCLUDE_FROM_ALL)
+  else()
+    message(FATAL_ERROR
+      "protobuf not found - please checkout a copy under external/.")
+  endif()
+endif(SPIRV_BUILD_FUZZER)
diff --git a/kokoro/scripts/linux/build.sh b/kokoro/scripts/linux/build.sh
index e89d2eae..f7b0fe14 100644
--- a/kokoro/scripts/linux/build.sh
+++ b/kokoro/scripts/linux/build.sh
@@ -71,13 +71,18 @@ git clone --depth=1 https://github.com/KhronosGroup/SPIRV-Headers external/spirv
 git clone --depth=1 https://github.com/google/googletest          external/googletest
 git clone --depth=1 https://github.com/google/effcee              external/effcee
 git clone --depth=1 https://github.com/google/re2                 external/re2
+git clone --depth=1 https://github.com/protocolbuffers/protobuf   external/protobuf
+pushd external/protobuf
+git fetch --all --tags --prune
+git checkout v3.7.1
+popd
 
 mkdir build && cd $SRC/build
 
 # Invoke the build.
 BUILD_SHA=${KOKORO_GITHUB_COMMIT:-$KOKORO_GITHUB_PULL_REQUEST_COMMIT}
 echo $(date): Starting build...
-cmake -DPYTHON_EXECUTABLE:FILEPATH=/usr/bin/python3 -GNinja -DCMAKE_INSTALL_PREFIX=$KOKORO_ARTIFACTS_DIR/install -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DRE2_BUILD_TESTING=OFF $ADDITIONAL_CMAKE_FLAGS $CMAKE_C_CXX_COMPILER ..
+cmake -DPYTHON_EXECUTABLE:FILEPATH=/usr/bin/python3 -GNinja -DCMAKE_INSTALL_PREFIX=$KOKORO_ARTIFACTS_DIR/install -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DRE2_BUILD_TESTING=OFF -DSPIRV_BUILD_FUZZER=ON $ADDITIONAL_CMAKE_FLAGS $CMAKE_C_CXX_COMPILER ..
 
 echo $(date): Build everything...
 ninja
diff --git a/kokoro/scripts/macos/build.sh b/kokoro/scripts/macos/build.sh
index 98e63668..5a3af43b 100644
--- a/kokoro/scripts/macos/build.sh
+++ b/kokoro/scripts/macos/build.sh
@@ -35,6 +35,11 @@ git clone --depth=1 https://github.com/KhronosGroup/SPIRV-Headers external/spirv
 git clone --depth=1 https://github.com/google/googletest          external/googletest
 git clone --depth=1 https://github.com/google/effcee              external/effcee
 git clone --depth=1 https://github.com/google/re2                 external/re2
+git clone --depth=1 https://github.com/protocolbuffers/protobuf   external/protobuf
+pushd external/protobuf
+git fetch --all --tags --prune
+git checkout v3.7.1
+popd
 
 mkdir build && cd $SRC/build
 
@@ -49,6 +54,7 @@ cmake \
   -DCMAKE_C_COMPILER=clang \
   -DCMAKE_CXX_COMPILER=clang++ \
   -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
+  -DSPIRV_BUILD_FUZZER=ON \
   ..
 
 echo $(date): Build everything...
diff --git a/kokoro/scripts/windows/build.bat b/kokoro/scripts/windows/build.bat
index 0532118f..ef2470d8 100644
--- a/kokoro/scripts/windows/build.bat
+++ b/kokoro/scripts/windows/build.bat
@@ -29,6 +29,11 @@ git clone --depth=1 https://github.com/KhronosGroup/SPIRV-Headers external/spirv
 git clone --depth=1 https://github.com/google/googletest          external/googletest
 git clone --depth=1 https://github.com/google/effcee              external/effcee
 git clone --depth=1 https://github.com/google/re2                 external/re2
+git clone --depth=1 https://github.com/protocolbuffers/protobuf   external/protobuf
+pushd external\protobuf
+git fetch --all --tags --prune
+git checkout v3.7.1
+popd
 
 :: #########################################
 :: set up msvc build env
@@ -65,6 +70,11 @@ if %VS_VERSION% == 2013 (
   set CMAKE_FLAGS=%CMAKE_FLAGS% -DSPIRV_SKIP_TESTS=ON
 )
 
+:: Skip building spirv-fuzz for VS2013; it relies on protobufs which VS2013 cannot handle.
+if %VS_VERSION% NEQ 2013 (
+  set CMAKE_FLAGS=%CMAKE_FLAGS% -DSPIRV_BUILD_FUZZER=ON
+)
+
 cmake %CMAKE_FLAGS% ..
 
 if %ERRORLEVEL% NEQ 0 exit /b %ERRORLEVEL%