diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 7b533a4..125b469 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -1,2 +1,3 @@
 [Hook Scripts]
+versioner = tools/versioner/preupload.sh
 notice = tools/update_notice.sh
diff --git a/libc/Android.bp b/libc/Android.bp
index 0d6f3cd..f663a97 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -2012,12 +2012,15 @@
     defaults: ["crt_defaults"],
 }
 
-preprocessed_ndk_headers {
-    name: "common_libc",
-    from: "include",
-    to: "",
-    license: "NOTICE",
-}
+// The following module lives in prebuilts/ndk because we need to preprocess the
+// headers to include ifdef guards for __ANDROID_API__. Update with
+// bionic/tools/update_headers.sh.
+// ndk_headers {
+//     name: "common_libc",
+//     from: "include",
+//     to: "",
+//     srcs: ["include/**/*.h"],
+// }
 
 ndk_headers {
     name: "libc_uapi",
diff --git a/libc/versioner-dependencies/arm/arch-arm b/libc/versioner-dependencies/arm/arch-arm
deleted file mode 120000
index cc94225..0000000
--- a/libc/versioner-dependencies/arm/arch-arm
+++ /dev/null
@@ -1 +0,0 @@
-../../arch-arm/include/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/arm/kernel_uapi_asm-arm b/libc/versioner-dependencies/arm/kernel_uapi_asm-arm
deleted file mode 120000
index 3c7584d..0000000
--- a/libc/versioner-dependencies/arm/kernel_uapi_asm-arm
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/asm-arm
\ No newline at end of file
diff --git a/libc/versioner-dependencies/arm64/arch-arm64 b/libc/versioner-dependencies/arm64/arch-arm64
deleted file mode 120000
index 2d9128a..0000000
--- a/libc/versioner-dependencies/arm64/arch-arm64
+++ /dev/null
@@ -1 +0,0 @@
-../../arch-arm64/include/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/arm64/kernel_uapi_asm-arm64 b/libc/versioner-dependencies/arm64/kernel_uapi_asm-arm64
deleted file mode 120000
index 7ee6fd2..0000000
--- a/libc/versioner-dependencies/arm64/kernel_uapi_asm-arm64
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/asm-arm64
\ No newline at end of file
diff --git a/libc/versioner-dependencies/common/clang-builtins b/libc/versioner-dependencies/common/clang-builtins
deleted file mode 120000
index 7bd481c..0000000
--- a/libc/versioner-dependencies/common/clang-builtins
+++ /dev/null
@@ -1 +0,0 @@
-../../../../external/clang/lib/Headers/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/common/kernel_android_uapi b/libc/versioner-dependencies/common/kernel_android_uapi
deleted file mode 120000
index fd78315..0000000
--- a/libc/versioner-dependencies/common/kernel_android_uapi
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/android/uapi/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/common/kernel_uapi b/libc/versioner-dependencies/common/kernel_uapi
deleted file mode 120000
index d5cb8ee..0000000
--- a/libc/versioner-dependencies/common/kernel_uapi
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/mips/arch-mips b/libc/versioner-dependencies/mips/arch-mips
deleted file mode 120000
index 56ed021..0000000
--- a/libc/versioner-dependencies/mips/arch-mips
+++ /dev/null
@@ -1 +0,0 @@
-../../arch-mips/include/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/mips/kernel_uapi_asm-mips b/libc/versioner-dependencies/mips/kernel_uapi_asm-mips
deleted file mode 120000
index 94bb3db..0000000
--- a/libc/versioner-dependencies/mips/kernel_uapi_asm-mips
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/asm-mips
\ No newline at end of file
diff --git a/libc/versioner-dependencies/mips64/arch-mips64 b/libc/versioner-dependencies/mips64/arch-mips64
deleted file mode 120000
index 4893b57..0000000
--- a/libc/versioner-dependencies/mips64/arch-mips64
+++ /dev/null
@@ -1 +0,0 @@
-../../arch-mips64/include/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/mips64/kernel_uapi_asm-mips b/libc/versioner-dependencies/mips64/kernel_uapi_asm-mips
deleted file mode 120000
index 94bb3db..0000000
--- a/libc/versioner-dependencies/mips64/kernel_uapi_asm-mips
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/asm-mips
\ No newline at end of file
diff --git a/libc/versioner-dependencies/x86/arch-x86 b/libc/versioner-dependencies/x86/arch-x86
deleted file mode 120000
index 6426384..0000000
--- a/libc/versioner-dependencies/x86/arch-x86
+++ /dev/null
@@ -1 +0,0 @@
-../../arch-x86/include/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/x86/kernel_uapi_asm-x86 b/libc/versioner-dependencies/x86/kernel_uapi_asm-x86
deleted file mode 120000
index 1b7a73d..0000000
--- a/libc/versioner-dependencies/x86/kernel_uapi_asm-x86
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/asm-x86/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/x86_64/arch-x86_64 b/libc/versioner-dependencies/x86_64/arch-x86_64
deleted file mode 120000
index 684d74e..0000000
--- a/libc/versioner-dependencies/x86_64/arch-x86_64
+++ /dev/null
@@ -1 +0,0 @@
-../../arch-x86_64/include/
\ No newline at end of file
diff --git a/libc/versioner-dependencies/x86_64/kernel_uapi_asm-x86 b/libc/versioner-dependencies/x86_64/kernel_uapi_asm-x86
deleted file mode 120000
index 1b7a73d..0000000
--- a/libc/versioner-dependencies/x86_64/kernel_uapi_asm-x86
+++ /dev/null
@@ -1 +0,0 @@
-../../kernel/uapi/asm-x86/
\ No newline at end of file
diff --git a/tools/update_headers.sh b/tools/update_headers.sh
new file mode 100755
index 0000000..0095d50
--- /dev/null
+++ b/tools/update_headers.sh
@@ -0,0 +1,53 @@
+#!/bin/bash
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+cd $DIR
+
+which versioner >/dev/null 2>&1
+if [ $? -ne 0 ]; then
+  >&2 echo "versioner not in path; run mma in $DIR/versioner"
+  exit 1
+fi
+
+VERSION=$(git rev-parse --short HEAD)
+git diff-index --quiet HEAD
+DIRTY=$?
+git branch -r --contains HEAD | grep -q aosp/master
+SUBMITTED=$?
+
+if [ $DIRTY -ne 0 ]; then
+  >&2 echo "Warning: bionic has uncommitted changes"
+  VERSION="${VERSION}-dirty"
+elif [ $SUBMITTED -ne 0 ]; then
+  >&2 echo "Warning: current HEAD does not exist in aosp/master"
+  VERSION="${VERSION}-unsubmitted"
+fi
+
+PREBUILTS_DIR=$ANDROID_BUILD_TOP/prebuilts/ndk
+BRANCH_NAME=$(git -C $PREBUILTS_DIR symbolic-ref --short -q HEAD)
+if [ $? -ne 0 ]; then
+  BRANCH_NAME=update-bionic-headers-$VERSION
+  echo "prebuilts/ndk has detached head; creating branch $BRANCH_NAME"
+  repo start $BRANCH_NAME $PREBUILTS_DIR
+else
+  echo "prebuilts/ndk already on branch $BRANCH_NAME"
+fi
+
+HEADERS_INSTALL=$PREBUILTS_DIR/headers
+if [ -d "$HEADERS_INSTALL" ]; then
+  git -C $PREBUILTS_DIR rm -r --ignore-unmatch $HEADERS_INSTALL
+  if [ -d $HEADERS_INSTALL ]; then
+    rm -r $HEADERS_INSTALL
+  fi
+fi
+
+versioner -p versioner/platforms versioner/current versioner/dependencies \
+  -o $HEADERS_INSTALL
+if [ $? -ne 0 ]; then
+  >&2 echo "Header preprocessing failed"
+  exit 1
+fi
+
+cp ../libc/NOTICE $PREBUILTS_DIR
+
+git -C $PREBUILTS_DIR add $HEADERS_INSTALL $PREBUILTS_DIR/NOTICE
+git -C $PREBUILTS_DIR commit -m "Update bionic headers to $VERSION."
diff --git a/tools/versioner/dependencies/arm/arch-arm b/tools/versioner/dependencies/arm/arch-arm
new file mode 120000
index 0000000..ed69f41
--- /dev/null
+++ b/tools/versioner/dependencies/arm/arch-arm
@@ -0,0 +1 @@
+../../../../libc/arch-arm/include
\ No newline at end of file
diff --git a/tools/versioner/dependencies/arm/kernel_uapi_asm-arm b/tools/versioner/dependencies/arm/kernel_uapi_asm-arm
new file mode 120000
index 0000000..fabed85
--- /dev/null
+++ b/tools/versioner/dependencies/arm/kernel_uapi_asm-arm
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi/asm-arm
\ No newline at end of file
diff --git a/tools/versioner/dependencies/arm64/arch-arm64 b/tools/versioner/dependencies/arm64/arch-arm64
new file mode 120000
index 0000000..21a21d4
--- /dev/null
+++ b/tools/versioner/dependencies/arm64/arch-arm64
@@ -0,0 +1 @@
+../../../../libc/arch-arm64/include
\ No newline at end of file
diff --git a/tools/versioner/dependencies/arm64/kernel_uapi_asm-arm64 b/tools/versioner/dependencies/arm64/kernel_uapi_asm-arm64
new file mode 120000
index 0000000..16e74a3
--- /dev/null
+++ b/tools/versioner/dependencies/arm64/kernel_uapi_asm-arm64
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi/asm-arm64
\ No newline at end of file
diff --git a/tools/versioner/dependencies/common/clang-builtins b/tools/versioner/dependencies/common/clang-builtins
new file mode 120000
index 0000000..fc27e65
--- /dev/null
+++ b/tools/versioner/dependencies/common/clang-builtins
@@ -0,0 +1 @@
+../../../../../external/clang/lib/Headers
\ No newline at end of file
diff --git a/tools/versioner/dependencies/common/kernel_android_uapi b/tools/versioner/dependencies/common/kernel_android_uapi
new file mode 120000
index 0000000..bcf6daa
--- /dev/null
+++ b/tools/versioner/dependencies/common/kernel_android_uapi
@@ -0,0 +1 @@
+../../../../libc/kernel/android/uapi
\ No newline at end of file
diff --git a/tools/versioner/dependencies/common/kernel_uapi b/tools/versioner/dependencies/common/kernel_uapi
new file mode 120000
index 0000000..2a915ef
--- /dev/null
+++ b/tools/versioner/dependencies/common/kernel_uapi
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi
\ No newline at end of file
diff --git a/tools/versioner/dependencies/mips/arch-mips b/tools/versioner/dependencies/mips/arch-mips
new file mode 120000
index 0000000..7f2f104
--- /dev/null
+++ b/tools/versioner/dependencies/mips/arch-mips
@@ -0,0 +1 @@
+../../../../libc/arch-mips/include
\ No newline at end of file
diff --git a/tools/versioner/dependencies/mips/kernel_uapi_asm-mips b/tools/versioner/dependencies/mips/kernel_uapi_asm-mips
new file mode 120000
index 0000000..dcd1955
--- /dev/null
+++ b/tools/versioner/dependencies/mips/kernel_uapi_asm-mips
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi/asm-mips
\ No newline at end of file
diff --git a/tools/versioner/dependencies/mips64/arch-mips64 b/tools/versioner/dependencies/mips64/arch-mips64
new file mode 120000
index 0000000..48cea72
--- /dev/null
+++ b/tools/versioner/dependencies/mips64/arch-mips64
@@ -0,0 +1 @@
+../../../../libc/arch-mips64/include
\ No newline at end of file
diff --git a/tools/versioner/dependencies/mips64/kernel_uapi_asm-mips b/tools/versioner/dependencies/mips64/kernel_uapi_asm-mips
new file mode 120000
index 0000000..dcd1955
--- /dev/null
+++ b/tools/versioner/dependencies/mips64/kernel_uapi_asm-mips
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi/asm-mips
\ No newline at end of file
diff --git a/tools/versioner/dependencies/x86/arch-x86 b/tools/versioner/dependencies/x86/arch-x86
new file mode 120000
index 0000000..d0f016a
--- /dev/null
+++ b/tools/versioner/dependencies/x86/arch-x86
@@ -0,0 +1 @@
+../../../../libc/arch-x86/include
\ No newline at end of file
diff --git a/tools/versioner/dependencies/x86/kernel_uapi_asm-x86 b/tools/versioner/dependencies/x86/kernel_uapi_asm-x86
new file mode 120000
index 0000000..0efae62
--- /dev/null
+++ b/tools/versioner/dependencies/x86/kernel_uapi_asm-x86
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi/asm-x86
\ No newline at end of file
diff --git a/tools/versioner/dependencies/x86_64/arch-x86_64 b/tools/versioner/dependencies/x86_64/arch-x86_64
new file mode 120000
index 0000000..deb647d
--- /dev/null
+++ b/tools/versioner/dependencies/x86_64/arch-x86_64
@@ -0,0 +1 @@
+../../../../libc/arch-x86_64/include
\ No newline at end of file
diff --git a/tools/versioner/dependencies/x86_64/kernel_uapi_asm-x86 b/tools/versioner/dependencies/x86_64/kernel_uapi_asm-x86
new file mode 120000
index 0000000..0efae62
--- /dev/null
+++ b/tools/versioner/dependencies/x86_64/kernel_uapi_asm-x86
@@ -0,0 +1 @@
+../../../../libc/kernel/uapi/asm-x86
\ No newline at end of file
diff --git a/tools/versioner/preupload.sh b/tools/versioner/preupload.sh
new file mode 100755
index 0000000..45d6cca
--- /dev/null
+++ b/tools/versioner/preupload.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+
+if ! which versioner > /dev/null; then
+  echo "versioner not found (lunch and mma in bionic)"
+  exit 1
+fi
+
+versioner -r arm -r arm64
+exit $?
diff --git a/tools/versioner/src/Android.bp b/tools/versioner/src/Android.bp
index 409bc10..d1362d0 100644
--- a/tools/versioner/src/Android.bp
+++ b/tools/versioner/src/Android.bp
@@ -41,6 +41,9 @@
                 "-fno-rtti",
             ],
         },
+        darwin: {
+            enabled: false,
+        },
         windows: {
             enabled: false,
         },