diff --git a/libc/kernel/tools/defaults.py b/libc/kernel/tools/defaults.py
index a71318e..2994e5e 100644
--- a/libc/kernel/tools/defaults.py
+++ b/libc/kernel/tools/defaults.py
@@ -25,6 +25,23 @@
     # Otherwise, there will be two struct timeval definitions when
     # __kernel_old_timeval is renamed to timeval.
     "__kernel_old_timeval": "1",
+    # Drop the custom byte swap functions and just use the clang builtins.
+    # https://github.com/android/ndk/issues/2107
+    "__arch_swab16": kCppUndefinedMacro,
+    "__arch_swab16p": kCppUndefinedMacro,
+    "__arch_swab16s": kCppUndefinedMacro,
+    "__arch_swab32": kCppUndefinedMacro,
+    "__arch_swab32p": kCppUndefinedMacro,
+    "__arch_swab32s": kCppUndefinedMacro,
+    "__arch_swab64": kCppUndefinedMacro,
+    "__arch_swab64p": kCppUndefinedMacro,
+    "__arch_swab64s": kCppUndefinedMacro,
+    "__arch_swahb32": kCppUndefinedMacro,
+    "__arch_swahb32p": kCppUndefinedMacro,
+    "__arch_swahb32s": kCppUndefinedMacro,
+    "__arch_swahw32": kCppUndefinedMacro,
+    "__arch_swahw32p": kCppUndefinedMacro,
+    "__arch_swahw32s": kCppUndefinedMacro,
     }
 
 # This is the set of known kernel data structures we want to remove from
@@ -133,9 +150,6 @@
           # These are required to support the above functions.
           "__fswahw32",
           "__fswahb32",
-          # As are these, for ILP32.
-          "__arch_swab32",
-          "__arch_swab64",
           # This is used by various macros in <linux/ioprio.h>.
           "ioprio_value",