diff --git a/base/Android.bp b/base/Android.bp
index f4a8411..7ff02a0 100644
--- a/base/Android.bp
+++ b/base/Android.bp
@@ -14,11 +14,10 @@
 // limitations under the License.
 //
 
-libbase_cppflags = [
-    "-Wall",
-    "-Wextra",
-    "-Werror",
-]
+cc_defaults {
+    name: "libbase_defaults",
+    cflags: ["-Wall", "-Werror", "-Wextra"],
+}
 
 cc_library_headers {
     name: "libbase_headers",
@@ -38,6 +37,7 @@
 
 cc_library {
     name: "libbase",
+    defaults: ["libbase_defaults"],
     vendor_available: true,
     host_supported: true,
     vndk: {
@@ -59,7 +59,6 @@
     ],
     export_header_lib_headers: ["libbase_headers"],
 
-    cppflags: libbase_cppflags,
     shared_libs: ["liblog"],
     target: {
         android: {
@@ -102,6 +101,7 @@
 // ------------------------------------------------------------------------------
 cc_test {
     name: "libbase_test",
+    defaults: ["libbase_defaults"],
     host_supported: true,
     srcs: [
         "endian_test.cpp",
@@ -133,7 +133,6 @@
         },
     },
     local_include_dirs: ["."],
-    cppflags: libbase_cppflags,
     shared_libs: ["libbase"],
     compile_multilib: "both",
     multilib: {
diff --git a/debuggerd/crasher/Android.bp b/debuggerd/crasher/Android.bp
index 67b4ab7..7bec470 100644
--- a/debuggerd/crasher/Android.bp
+++ b/debuggerd/crasher/Android.bp
@@ -1,7 +1,7 @@
 cc_defaults {
     name: "crasher-defaults",
 
-    cppflags: [
+    cflags: [
         "-W",
         "-Wall",
         "-Wextra",
diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index 5a6298e..ed165ed 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -20,7 +20,11 @@
         misc_undefined: ["integer"],
     },
     local_include_dirs: ["include/"],
-    cppflags: ["-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-variable",
+    ],
 }
 
 cc_library_static {
diff --git a/init/Android.bp b/init/Android.bp
index 8c4f005..45ee754 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -20,7 +20,7 @@
     sanitize: {
         misc_undefined: ["signed-integer-overflow"],
     },
-    cppflags: [
+    cflags: [
         "-DLOG_UEVENTS=0",
         "-Wall",
         "-Wextra",
diff --git a/init/test_service/Android.bp b/init/test_service/Android.bp
index 9bd6f27..6399699 100644
--- a/init/test_service/Android.bp
+++ b/init/test_service/Android.bp
@@ -17,6 +17,7 @@
 cc_binary {
     name: "test_service",
     srcs: ["test_service.cpp"],
+    cflags: ["-Wall", "-Werror"],
     shared_libs: ["libbase"],
     init_rc: ["test_service.rc"],
 }
diff --git a/init/test_service/test_service.cpp b/init/test_service/test_service.cpp
index e7206f8..71d1ea4 100644
--- a/init/test_service/test_service.cpp
+++ b/init/test_service/test_service.cpp
@@ -59,7 +59,6 @@
     }
 
     bool test_fails = false;
-    size_t uargc = static_cast<size_t>(argc);  // |argc| >= 3.
     for (size_t i = 1; i < static_cast<size_t>(argc); i = i + 2) {
         std::string expected_value = argv[i + 1];
         auto f = fields.find(argv[i]);
diff --git a/libasyncio/Android.bp b/libasyncio/Android.bp
index 9a637ac..9a12f0d 100644
--- a/libasyncio/Android.bp
+++ b/libasyncio/Android.bp
@@ -14,20 +14,19 @@
 // limitations under the License.
 //
 
-libasyncio_cppflags = [
-    "-Wall",
-    "-Wextra",
-    "-Werror",
-]
+cc_defaults {
+    name: "libasyncio_defaults",
+    cflags: ["-Wall", "-Werror", "-Wextra"],
+}
 
 cc_library {
     name: "libasyncio",
+    defaults: ["libasyncio_defaults"],
     vendor_available: true,
     host_supported: true,
     srcs: [
         "AsyncIO.cpp",
     ],
-    cppflags: libasyncio_cppflags,
 
     export_include_dirs: ["include"],
     target: {
diff --git a/libgrallocusage/Android.bp b/libgrallocusage/Android.bp
index cf03868..bcc0616 100644
--- a/libgrallocusage/Android.bp
+++ b/libgrallocusage/Android.bp
@@ -15,9 +15,12 @@
 cc_library_static {
     name: "libgrallocusage",
     vendor_available: true,
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
     cppflags: [
         "-Weverything",
-        "-Werror",
         "-Wno-c++98-compat-pedantic",
         // Hide errors in headers we include
         "-Wno-global-constructors",
diff --git a/libpackagelistparser/Android.bp b/libpackagelistparser/Android.bp
index a9fec7d..3d202fc 100644
--- a/libpackagelistparser/Android.bp
+++ b/libpackagelistparser/Android.bp
@@ -2,6 +2,7 @@
 
     name: "libpackagelistparser",
     srcs: ["packagelistparser.c"],
+    cflags: ["-Wall", "-Werror"],
     shared_libs: ["liblog"],
     local_include_dirs: ["include"],
     export_include_dirs: ["include"],
diff --git a/libprocinfo/Android.bp b/libprocinfo/Android.bp
index b568ee5..1cfabd5 100644
--- a/libprocinfo/Android.bp
+++ b/libprocinfo/Android.bp
@@ -14,14 +14,14 @@
 // limitations under the License.
 //
 
-libprocinfo_cppflags = [
-    "-Wall",
-    "-Wextra",
-    "-Werror",
-]
+cc_defaults {
+    name: "libprocinfo_defaults",
+    cflags: ["-Wall", "-Werror", "-Wextra"],
+}
 
 cc_library {
     name: "libprocinfo",
+    defaults: ["libprocinfo_defaults"],
     vendor_available: true,
     vndk: {
         enabled: true,
@@ -30,7 +30,6 @@
     srcs: [
         "process.cpp",
     ],
-    cppflags: libprocinfo_cppflags,
 
     local_include_dirs: ["include"],
     export_include_dirs: ["include"],
@@ -52,6 +51,7 @@
 // ------------------------------------------------------------------------------
 cc_test {
     name: "libprocinfo_test",
+    defaults: ["libprocinfo_defaults"],
     host_supported: true,
     srcs: [
         "process_test.cpp",
@@ -65,7 +65,6 @@
         },
     },
 
-    cppflags: libprocinfo_cppflags,
     shared_libs: ["libbase", "libprocinfo"],
 
     compile_multilib: "both",
diff --git a/libutils/Android.bp b/libutils/Android.bp
index b70845b..4bd2a98 100644
--- a/libutils/Android.bp
+++ b/libutils/Android.bp
@@ -75,7 +75,7 @@
         "misc.cpp",
     ],
 
-    cflags: ["-Werror"],
+    cflags: ["-Wall", "-Werror"],
     include_dirs: ["external/safe-iop/include"],
     header_libs: [
         "libutils_headers",
@@ -154,6 +154,7 @@
     static_libs: ["libutils"],
     shared_libs: ["liblog"],
     srcs: ["SharedBufferTest.cpp"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 subdirs = ["tests"]
diff --git a/libutils/RefBase.cpp b/libutils/RefBase.cpp
index f5f881f..8bccb0f 100644
--- a/libutils/RefBase.cpp
+++ b/libutils/RefBase.cpp
@@ -410,8 +410,7 @@
         return;
     }
 
-    int32_t old = refs->mStrong.fetch_sub(INITIAL_STRONG_VALUE,
-            std::memory_order_relaxed);
+    int32_t old __unused = refs->mStrong.fetch_sub(INITIAL_STRONG_VALUE, std::memory_order_relaxed);
     // A decStrong() must still happen after us.
     ALOG_ASSERT(old > INITIAL_STRONG_VALUE, "0x%x too small", old);
     refs->mBase->onFirstRef();
diff --git a/libutils/StopWatch.cpp b/libutils/StopWatch.cpp
index 219c13c..d01865e 100644
--- a/libutils/StopWatch.cpp
+++ b/libutils/StopWatch.cpp
@@ -30,10 +30,7 @@
 
 namespace android {
 
-
-StopWatch::StopWatch(const char *name, int clock, uint32_t flags)
-    :   mName(name), mClock(clock), mFlags(flags)
-{
+StopWatch::StopWatch(const char* name, int clock) : mName(name), mClock(clock) {
     reset();
 }
 
diff --git a/libutils/include/utils/StopWatch.h b/libutils/include/utils/StopWatch.h
index 693dd3c..76d78d0 100644
--- a/libutils/include/utils/StopWatch.h
+++ b/libutils/include/utils/StopWatch.h
@@ -29,21 +29,18 @@
 class StopWatch
 {
 public:
-        StopWatch(  const char *name,
-                    int clock = SYSTEM_TIME_MONOTONIC,
-                    uint32_t flags = 0);
-        ~StopWatch();
-        
-        const char* name() const;
-        nsecs_t     lap();
-        nsecs_t     elapsedTime() const;
+  StopWatch(const char* name, int clock = SYSTEM_TIME_MONOTONIC);
+  ~StopWatch();
 
-        void        reset();
-        
+  const char* name() const;
+  nsecs_t lap();
+  nsecs_t elapsedTime() const;
+
+  void reset();
+
 private:
     const char*     mName;
     int             mClock;
-    uint32_t        mFlags;
     
     struct lap_t {
         nsecs_t     soFar;
diff --git a/libutils/tests/Android.bp b/libutils/tests/Android.bp
index a891fca..a3e7ffe 100644
--- a/libutils/tests/Android.bp
+++ b/libutils/tests/Android.bp
@@ -77,6 +77,7 @@
     host_supported: true,
     relative_install_path: "libutils_tests",
     srcs: ["Singleton_test1.cpp"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 cc_test_library {
@@ -84,5 +85,6 @@
     host_supported: true,
     relative_install_path: "libutils_tests",
     srcs: ["Singleton_test2.cpp"],
+    cflags: ["-Wall", "-Werror"],
     shared_libs: ["libutils_tests_singleton1"],
 }
diff --git a/libvndksupport/Android.bp b/libvndksupport/Android.bp
index b624223..fec79b7 100644
--- a/libvndksupport/Android.bp
+++ b/libvndksupport/Android.bp
@@ -3,6 +3,7 @@
 cc_library {
     name: "libvndksupport",
     srcs: ["linker.c"],
+    cflags: ["-Wall", "-Werror"],
     local_include_dirs: ["include/vndksupport"],
     export_include_dirs: ["include"],
     shared_libs: ["liblog"],
diff --git a/libvndksupport/tests/Android.bp b/libvndksupport/tests/Android.bp
index 3587cf8..5b467f8 100644
--- a/libvndksupport/tests/Android.bp
+++ b/libvndksupport/tests/Android.bp
@@ -17,6 +17,7 @@
     srcs: [
         "linker_test.cpp",
     ],
+    cflags: ["-Wall", "-Werror"],
 
     host_supported: false,
     shared_libs: [
diff --git a/trusty/keymaster/Android.bp b/trusty/keymaster/Android.bp
index 6b9d723..7735684 100644
--- a/trusty/keymaster/Android.bp
+++ b/trusty/keymaster/Android.bp
@@ -30,6 +30,7 @@
         "trusty_keymaster_ipc.cpp",
         "trusty_keymaster_main.cpp",
     ],
+    cflags: ["-Wall", "-Werror"],
     shared_libs: [
         "libcrypto",
         "libcutils",
diff --git a/trusty/keymaster/trusty_keymaster_main.cpp b/trusty/keymaster/trusty_keymaster_main.cpp
index 9c2ae2d..ed78b7f 100644
--- a/trusty/keymaster/trusty_keymaster_main.cpp
+++ b/trusty/keymaster/trusty_keymaster_main.cpp
@@ -289,7 +289,6 @@
     std::unique_ptr<const uint8_t[]> deleter(key.key_material);
 
     printf("=== Signing with imported ECDSA key ===\n");
-    keymaster_ec_sign_params_t sign_params = {DIGEST_NONE};
     size_t message_len = 30 /* arbitrary */;
     std::unique_ptr<uint8_t[]> message(new uint8_t[message_len]);
     memset(message.get(), 'a', message_len);
diff --git a/trusty/libtrusty/Android.bp b/trusty/libtrusty/Android.bp
index f316da2..1a8db2f 100644
--- a/trusty/libtrusty/Android.bp
+++ b/trusty/libtrusty/Android.bp
@@ -21,6 +21,7 @@
 
     srcs: ["trusty.c"],
     export_include_dirs: ["include"],
+    cflags: ["-Wall", "-Werror"],
 
     shared_libs: ["liblog"],
 }
diff --git a/trusty/libtrusty/tipc-test/Android.bp b/trusty/libtrusty/tipc-test/Android.bp
index cb00fe7..6ec8c23 100644
--- a/trusty/libtrusty/tipc-test/Android.bp
+++ b/trusty/libtrusty/tipc-test/Android.bp
@@ -23,4 +23,5 @@
         "liblog",
     ],
     gtest: false,
+    cflags: ["-Wall", "-Werror"],
 }