diff --git a/libc/Android.mk b/libc/Android.mk
index 92ead26..61bdf7e 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -692,6 +692,7 @@
 LOCAL_SYSTEM_SHARED_LIBRARIES :=
 
 $(eval $(call patch-up-arch-specific-flags,LOCAL_CFLAGS,libc_common_cflags))
+$(eval $(call patch-up-arch-specific-flags,LOCAL_SRC_FILES,libc_freebsd_src_files))
 include $(BUILD_STATIC_LIBRARY)
 
 
@@ -760,6 +761,7 @@
 LOCAL_SYSTEM_SHARED_LIBRARIES :=
 
 $(eval $(call patch-up-arch-specific-flags,LOCAL_CFLAGS,libc_common_cflags))
+$(eval $(call patch-up-arch-specific-flags,LOCAL_SRC_FILES,libc_openbsd_src_files))
 include $(BUILD_STATIC_LIBRARY)
 
 
diff --git a/libc/arch-arm/arm.mk b/libc/arch-arm/arm.mk
index 8c5e681..b5ed7f0 100644
--- a/libc/arch-arm/arm.mk
+++ b/libc/arch-arm/arm.mk
@@ -1,22 +1,35 @@
-# arm specific configs
+# 32-bit arm.
 
-# These are used by the 32-bit targets, but not the 64-bit ones.
-libc_common_src_files_arm := \
+#
+# Various kinds of LP32 cruft.
+#
+
+libc_bionic_src_files_arm += \
+    bionic/mmap.cpp \
+
+libc_common_src_files_arm += \
     bionic/legacy_32_bit_support.cpp \
     bionic/ndk_cruft.cpp \
     bionic/time64.c \
+
+libc_netbsd_src_files_arm += \
+    upstream-netbsd/common/lib/libc/hash/sha1/sha1.c \
+
+libc_openbsd_src_files_arm += \
     upstream-openbsd/lib/libc/stdio/putw.c \
 
-# These are shared by all the 32-bit targets, but not the 64-bit ones.
-libc_bionic_src_files_arm := \
-    bionic/mmap.cpp
+#
+# Default implementations of functions that are commonly optimized.
+#
 
-libc_common_src_files_arm += \
+libc_bionic_src_files_arm += \
     bionic/memchr.c \
     bionic/memrchr.c \
     bionic/strchr.cpp \
     bionic/strnlen.c \
     bionic/strrchr.cpp \
+
+libc_freebsd_src_files_arm += \
     upstream-freebsd/lib/libc/string/wcscat.c \
     upstream-freebsd/lib/libc/string/wcschr.c \
     upstream-freebsd/lib/libc/string/wcscmp.c \
@@ -25,6 +38,8 @@
     upstream-freebsd/lib/libc/string/wcsrchr.c \
     upstream-freebsd/lib/libc/string/wmemcmp.c \
     upstream-freebsd/lib/libc/string/wmemmove.c \
+
+libc_openbsd_src_files_arm += \
     upstream-openbsd/lib/libc/string/bcopy.c \
     upstream-openbsd/lib/libc/string/stpcpy.c \
     upstream-openbsd/lib/libc/string/stpncpy.c \
@@ -34,18 +49,10 @@
     upstream-openbsd/lib/libc/string/strncmp.c \
     upstream-openbsd/lib/libc/string/strncpy.c \
 
-# The C++ fortify function implementations for which there is an
-# arm assembler version.
 #
-# Fortify implementations of libc functions.
-# libc_common_src_files_arm +=
-#    bionic/__memcpy_chk.cpp \
-#    bionic/__memset_chk.cpp \
-#    bionic/__strcpy_chk.cpp \
-#    bionic/__strcat_chk.cpp \
+# Inherently architecture-specific code.
+#
 
-##########################################
-### CPU specific source files
 libc_bionic_src_files_arm += \
     arch-arm/bionic/abort_arm.S \
     arch-arm/bionic/atomics_arm.c \
@@ -62,9 +69,6 @@
 libc_arch_static_src_files_arm := arch-arm/bionic/exidx_static.c
 libc_arch_dynamic_src_files_arm := arch-arm/bionic/exidx_dynamic.c
 
-libc_netbsd_src_files_arm := \
-    upstream-netbsd/common/lib/libc/hash/sha1/sha1.c \
-
 ## CPU variant specific source files
 ifeq ($(strip $(TARGET_$(my_2nd_arch_prefix)CPU_VARIANT)),)
   $(warning TARGET_$(my_2nd_arch_prefix)ARCH is arm, but TARGET_$(my_2nd_arch_prefix)CPU_VARIANT is not defined)
diff --git a/libc/arch-arm64/arm64.mk b/libc/arch-arm64/arm64.mk
index 692aaf6..cdb2777 100644
--- a/libc/arch-arm64/arm64.mk
+++ b/libc/arch-arm64/arm64.mk
@@ -1,8 +1,18 @@
-# arm64 specific configs
+# 64-bit arm.
 
-libc_common_src_files_arm64 := \
+#
+# Default implementations of functions that are commonly optimized.
+#
+
+libc_bionic_src_files_arm64 += \
+    bionic/__memcpy_chk.cpp \
+    bionic/__memset_chk.cpp \
+    bionic/__strcpy_chk.cpp \
+    bionic/__strcat_chk.cpp \
     bionic/memrchr.c \
     bionic/strrchr.cpp \
+
+libc_freebsd_src_files_arm64 += \
     upstream-freebsd/lib/libc/string/wcscat.c \
     upstream-freebsd/lib/libc/string/wcschr.c \
     upstream-freebsd/lib/libc/string/wcscmp.c \
@@ -10,6 +20,8 @@
     upstream-freebsd/lib/libc/string/wcslen.c \
     upstream-freebsd/lib/libc/string/wcsrchr.c \
     upstream-freebsd/lib/libc/string/wmemcmp.c \
+
+libc_openbsd_src_files_arm64 += \
     upstream-openbsd/lib/libc/string/stpncpy.c \
     upstream-openbsd/lib/libc/string/strcat.c \
     upstream-openbsd/lib/libc/string/strlcat.c \
@@ -17,16 +29,11 @@
     upstream-openbsd/lib/libc/string/strncat.c \
     upstream-openbsd/lib/libc/string/strncpy.c \
 
-# Fortify implementations of libc functions.
-libc_common_src_files_arm64 += \
-    bionic/__memcpy_chk.cpp \
-    bionic/__memset_chk.cpp \
-    bionic/__strcpy_chk.cpp \
-    bionic/__strcat_chk.cpp \
+#
+# Inherently architecture-specific code.
+#
 
-##########################################
-### CPU specific source files
-libc_bionic_src_files_arm64 := \
+libc_bionic_src_files_arm64 += \
     arch-arm64/bionic/__bionic_clone.S \
     arch-arm64/bionic/_exit_with_stack_teardown.S \
     arch-arm64/bionic/_setjmp.S \
diff --git a/libc/arch-mips/mips.mk b/libc/arch-mips/mips.mk
index 31a1f32..ac75a4b 100644
--- a/libc/arch-mips/mips.mk
+++ b/libc/arch-mips/mips.mk
@@ -1,17 +1,32 @@
-# mips specific configs
+# 32-bit mips.
 
-# These are shared by all the 32-bit targets, but not the 64-bit ones.
-libc_common_src_files_mips := \
+#
+# Various kinds of LP32 cruft.
+#
+
+libc_bionic_src_files_mips += \
+    bionic/mmap.cpp \
+
+libc_common_src_files_mips += \
     bionic/legacy_32_bit_support.cpp \
     bionic/ndk_cruft.cpp \
     bionic/time64.c \
+
+libc_netbsd_src_files_mips += \
+    upstream-netbsd/common/lib/libc/hash/sha1/sha1.c \
+
+libc_openbsd_src_files_mips += \
     upstream-openbsd/lib/libc/stdio/putw.c \
 
-# These are shared by all the 32-bit targets, but not the 64-bit ones.
-libc_bionic_src_files_mips += \
-     bionic/mmap.cpp
+#
+# Default implementations of functions that are commonly optimized.
+#
 
-libc_common_src_files_mips += \
+libc_bionic_src_files_mips += \
+    bionic/__memcpy_chk.cpp \
+    bionic/__memset_chk.cpp \
+    bionic/__strcpy_chk.cpp \
+    bionic/__strcat_chk.cpp \
     bionic/memchr.c \
     bionic/memcmp.c \
     bionic/memmove.c \
@@ -19,6 +34,8 @@
     bionic/strchr.cpp \
     bionic/strnlen.c \
     bionic/strrchr.cpp \
+
+libc_freebsd_src_files_mips += \
     upstream-freebsd/lib/libc/string/wcscat.c \
     upstream-freebsd/lib/libc/string/wcschr.c \
     upstream-freebsd/lib/libc/string/wcscmp.c \
@@ -27,6 +44,8 @@
     upstream-freebsd/lib/libc/string/wcsrchr.c \
     upstream-freebsd/lib/libc/string/wmemcmp.c \
     upstream-freebsd/lib/libc/string/wmemmove.c \
+
+libc_openbsd_src_files_mips += \
     upstream-openbsd/lib/libc/string/bcopy.c \
     upstream-openbsd/lib/libc/string/stpcpy.c \
     upstream-openbsd/lib/libc/string/stpncpy.c \
@@ -39,16 +58,10 @@
     upstream-openbsd/lib/libc/string/strncmp.c \
     upstream-openbsd/lib/libc/string/strncpy.c \
 
-# Fortify implementations of libc functions.
-libc_common_src_files_mips += \
-    bionic/__memcpy_chk.cpp \
-    bionic/__memset_chk.cpp \
-    bionic/__strcpy_chk.cpp \
-    bionic/__strcat_chk.cpp \
+#
+# Inherently architecture-specific code.
+#
 
-
-##########################################
-### CPU specific source files
 libc_bionic_src_files_mips += \
     arch-mips/bionic/__bionic_clone.S \
     arch-mips/bionic/bzero.S \
@@ -69,13 +82,12 @@
 else
 libc_bionic_src_files_mips += \
     bionic/memcpy.cpp \
-    bionic/memset.c
-libc_common_src_files_mips += \
-    upstream-openbsd/lib/libc/string/strlen.c
-endif
+    bionic/memset.c \
 
-libc_netbsd_src_files_mips := \
-    upstream-netbsd/common/lib/libc/hash/sha1/sha1.c \
+libc_openbsd_src_files_mips += \
+    upstream-openbsd/lib/libc/string/strlen.c \
+
+endif
 
 libc_crt_target_cflags_mips := \
     $($(my_2nd_arch_prefix)TARGET_GLOBAL_CFLAGS) \
diff --git a/libc/arch-mips64/mips64.mk b/libc/arch-mips64/mips64.mk
index 230cb26..0d4b727 100644
--- a/libc/arch-mips64/mips64.mk
+++ b/libc/arch-mips64/mips64.mk
@@ -1,13 +1,25 @@
-# mips64 specific configs
+# 64-bit mips.
 
-libc_common_src_files_mips64 := \
+#
+# Default implementations of functions that are commonly optimized.
+#
+
+libc_bionic_src_files_mips64 += \
+    bionic/__memcpy_chk.cpp \
+    bionic/__memset_chk.cpp \
+    bionic/__strcpy_chk.cpp \
+    bionic/__strcat_chk.cpp \
     bionic/memchr.c \
     bionic/memcmp.c \
+    bionic/memcpy.cpp \
     bionic/memmove.c \
     bionic/memrchr.c \
+    bionic/memset.c \
     bionic/strchr.cpp \
     bionic/strnlen.c \
     bionic/strrchr.cpp \
+
+libc_freebsd_src_files_mips64 += \
     upstream-freebsd/lib/libc/string/wcscat.c \
     upstream-freebsd/lib/libc/string/wcschr.c \
     upstream-freebsd/lib/libc/string/wcscmp.c \
@@ -16,6 +28,8 @@
     upstream-freebsd/lib/libc/string/wcsrchr.c \
     upstream-freebsd/lib/libc/string/wmemcmp.c \
     upstream-freebsd/lib/libc/string/wmemmove.c \
+
+libc_openbsd_src_files_mips64 += \
     upstream-openbsd/lib/libc/string/stpcpy.c \
     upstream-openbsd/lib/libc/string/stpncpy.c \
     upstream-openbsd/lib/libc/string/strcat.c \
@@ -28,17 +42,11 @@
     upstream-openbsd/lib/libc/string/strncmp.c \
     upstream-openbsd/lib/libc/string/strncpy.c \
 
-# Fortify implementations of libc functions.
-libc_common_src_files_mips64 += \
-    bionic/__memcpy_chk.cpp \
-    bionic/__memset_chk.cpp \
-    bionic/__strcpy_chk.cpp \
-    bionic/__strcat_chk.cpp \
+#
+# Inherently architecture-specific code.
+#
 
-
-##########################################
-### CPU specific source files
-libc_bionic_src_files_mips64 := \
+libc_bionic_src_files_mips64 += \
     arch-mips64/bionic/__bionic_clone.S \
     arch-mips64/bionic/_exit_with_stack_teardown.S \
     arch-mips64/bionic/__get_sp.S \
@@ -48,25 +56,18 @@
     arch-mips64/bionic/syscall.S \
     arch-mips64/bionic/vfork.S \
 
-# FIXME TODO
-## libc_bionic_src_files_mips64 += arch-mips64/string/memcpy.S
-## libc_bionic_src_files_mips64 += arch-mips64/string/memset.S
-libc_bionic_src_files_mips64 += bionic/memcpy.cpp
-libc_bionic_src_files_mips64 += bionic/memset.c
-
-
 libc_crt_target_cflags_mips64 := \
     $($(my_2nd_arch_prefix)TARGET_GLOBAL_CFLAGS) \
-    -I$(LOCAL_PATH)/arch-mips64/include
+    -I$(LOCAL_PATH)/arch-mips64/include \
 
 libc_crt_target_crtbegin_file_mips64 := \
-    $(LOCAL_PATH)/arch-mips64/bionic/crtbegin.c
+    $(LOCAL_PATH)/arch-mips64/bionic/crtbegin.c \
 
 libc_crt_target_crtbegin_so_file_mips64 := \
-    $(LOCAL_PATH)/arch-common/bionic/crtbegin_so.c
+    $(LOCAL_PATH)/arch-common/bionic/crtbegin_so.c \
 
 libc_crt_target_so_cflags_mips64 := \
-    -fPIC
+    -fPIC \
 
 libc_crt_target_ldflags_mips64 := \
-    -melf64ltsmip
+    -melf64ltsmip \
diff --git a/libc/arch-x86/x86.mk b/libc/arch-x86/x86.mk
index d90b1ce..2c90317 100644
--- a/libc/arch-x86/x86.mk
+++ b/libc/arch-x86/x86.mk
@@ -1,27 +1,40 @@
-# x86 specific configs
+# 32-bit x86.
 
-# These are shared by all the 32-bit targets, but not the 64-bit ones.
-libc_common_src_files_x86 := \
+#
+# Various kinds of LP32 cruft.
+#
+
+libc_bionic_src_files_x86 += \
+    bionic/mmap.cpp \
+
+libc_common_src_files_x86 += \
     bionic/legacy_32_bit_support.cpp \
     bionic/ndk_cruft.cpp \
     bionic/time64.c \
+
+libc_netbsd_src_files_x86 += \
+    upstream-netbsd/common/lib/libc/hash/sha1/sha1.c \
+
+libc_openbsd_src_files_x86 += \
     upstream-openbsd/lib/libc/stdio/putw.c \
 
-# Fortify implementations of libc functions.
+#
+# Default implementations of functions that are commonly optimized.
+#
+
 libc_common_src_files_x86 += \
     bionic/__memcpy_chk.cpp \
     bionic/__memset_chk.cpp \
     bionic/__strcpy_chk.cpp \
     bionic/__strcat_chk.cpp \
+
+libc_freebsd_src_files_x86 += \
     upstream-freebsd/lib/libc/string/wmemmove.c \
 
+#
+# Inherently architecture-specific functions.
+#
 
-# These are shared by all the 32-bit targets, but not the 64-bit ones.
-libc_bionic_src_files_x86 := \
-    bionic/mmap.cpp
-
-##########################################
-### CPU specific source files
 libc_bionic_src_files_x86 += \
     arch-x86/bionic/__bionic_clone.S \
     arch-x86/bionic/_exit_with_stack_teardown.S \
@@ -42,9 +55,6 @@
 include $(arch_variant_mk)
 libc_common_additional_dependencies += $(arch_variant_mk)
 
-libc_netbsd_src_files_x86 := \
-    upstream-netbsd/common/lib/libc/hash/sha1/sha1.c \
-
 arch_variant_mk :=
 
 libc_crt_target_cflags_x86 := \
diff --git a/libc/arch-x86_64/x86_64.mk b/libc/arch-x86_64/x86_64.mk
index 5f12a49..8675ef4 100644
--- a/libc/arch-x86_64/x86_64.mk
+++ b/libc/arch-x86_64/x86_64.mk
@@ -1,11 +1,21 @@
-# x86_64 specific configs
+# 64-bit x86.
 
-libc_common_src_files_x86_64 := \
+#
+# Default implementations of functions that are commonly optimized.
+#
+
+libc_bionic_src_files_x86_64 += \
+    bionic/__memcpy_chk.cpp \
+    bionic/__memset_chk.cpp \
+    bionic/__strcpy_chk.cpp \
+    bionic/__strcat_chk.cpp \
     bionic/memchr.c \
     bionic/memrchr.c \
     bionic/strchr.cpp \
     bionic/strnlen.c \
     bionic/strrchr.cpp \
+
+libc_freebsd_src_files_x86_64 += \
     upstream-freebsd/lib/libc/string/wcscat.c \
     upstream-freebsd/lib/libc/string/wcschr.c \
     upstream-freebsd/lib/libc/string/wcscmp.c \
@@ -14,20 +24,16 @@
     upstream-freebsd/lib/libc/string/wcsrchr.c \
     upstream-freebsd/lib/libc/string/wmemcmp.c \
     upstream-freebsd/lib/libc/string/wmemmove.c \
+
+libc_openbsd_src_files_x86_64 += \
     upstream-openbsd/lib/libc/string/strlcat.c \
     upstream-openbsd/lib/libc/string/strlcpy.c \
 
-# Fortify implementations of libc functions.
-libc_common_src_files_x86_64 += \
-    bionic/__memcpy_chk.cpp \
-    bionic/__memset_chk.cpp \
-    bionic/__strcpy_chk.cpp \
-    bionic/__strcat_chk.cpp \
+#
+# Inherently architecture-specific code.
+#
 
-
-##########################################
-### CPU specific source files
-libc_bionic_src_files_x86_64 := \
+libc_bionic_src_files_x86_64 += \
     arch-x86_64/bionic/__bionic_clone.S \
     arch-x86_64/bionic/_exit_with_stack_teardown.S \
     arch-x86_64/bionic/__restore_rt.S \
@@ -38,6 +44,10 @@
     arch-x86_64/bionic/syscall.S \
     arch-x86_64/bionic/vfork.S \
 
+#
+# Optimized memory/string functions.
+#
+
 libc_bionic_src_files_x86_64 += \
     arch-x86_64/string/sse2-memcpy-slm.S \
     arch-x86_64/string/sse2-memmove-slm.S \
@@ -55,15 +65,15 @@
 
 libc_crt_target_cflags_x86_64 += \
     -m64 \
-    -I$(LOCAL_PATH)/arch-x86_64/include
+    -I$(LOCAL_PATH)/arch-x86_64/include \
 
-libc_crt_target_ldflags_x86_64 := -melf_x86_64
+libc_crt_target_ldflags_x86_64 := -melf_x86_64 \
 
 libc_crt_target_crtbegin_file_x86_64 := \
-    $(LOCAL_PATH)/arch-common/bionic/crtbegin.c
+    $(LOCAL_PATH)/arch-common/bionic/crtbegin.c \
 
 libc_crt_target_crtbegin_so_file_x86_64 := \
-    $(LOCAL_PATH)/arch-common/bionic/crtbegin_so.c
+    $(LOCAL_PATH)/arch-common/bionic/crtbegin_so.c \
 
 libc_crt_target_so_cflags_x86_64 := \
-    -fPIC
+    -fPIC \