The standard build of u-boot works!

#Instructions taken from https://github.com/csimmonds/a4b-scripts/blob/master/write-sdcard-beagleboneblack.sh

mkimage -A arm -O linux -T ramdisk -d out/target/product/beagleboneblack/ramdisk.img uRamdisk

# I used gparted to create these partitions
# Create 4 primary partitons on the sd card
# 1: boot: FAT32, 64 MiB, boot flag
# 2: system: Linux, 512 MiB
# 3: data: Linux, 3072 MiB
# 4: cache: Linux, 256 MiB

sudo cp uRamdisk /media/jeramy/BOOT
cd ../BBB/u-boot_stock
cp MLO /media/jeramy/BOOT
cp u-boot.img /media/jeramy/BOOT
cp ~/android-AOSP/device/ti/beagleboneblack/uEnv.txt /media/jeramy/BOOT
cd ../

# http://elinux.org/BeagleBone_DTBs
cat bb-kernel/KERNEL/arch/arm/boot/zImage bb-kernel/KERNEL/arch/arm/boot/dts/am335x-boneblack-hdmi-overlay.dtb > zImage-dtb-hdmi

bb-kernel/KERNEL/scripts/mkuboot.sh -A arm -O linux -C none -T kernel -a 0x80008000 -e 0x80008000 -n 'Linux-4.4' -d zImage-dtb-hdmi uImage-dtb-hdmi

sudo cp uImage-dtb-hdmi /media/jeramy/BOOT/uImage
sudo umount /media/jeramy/BOOT

# I used `disks` to restore images to the appropriate partition

#~/android-AOSP/out/target/product/beagleboneblack/system.img
#~/android-AOSP/out/target/product/beagleboneblack/cache.img
#~/android-AOSP/out/target/product/beagleboneblack/userdata.img

jeramy@jeramy-pc2:~/BBB$ adb devices -l
List of devices attached
123456789 device usb:2-2 product:beagleboneblack_sd model:BeagleBone_Black_on_SD_card device:beagleboneblack

jeramy@jeramy-pc2:~/BBB$ adb shell
root@beagleboneblack:/ #

root@beagleboneblack:/ # cat /proc/version
Linux version 4.4.53-bone16 (jeramy@jeramy-pc2) (gcc version 5.4.1 20161213 (Linaro GCC 5.4-2017.01) ) #1 SMP Wed Mar 15 17:46:44 EDT 2017

root@beagleboneblack:/ # getprop ro.build.version.release
6.0.1
root@beagleboneblack:/ # getprop ro.build.version.sdk
23
root@beagleboneblack:/ # getprop
[dalvik.vm.dex2oat-Xms]: [64m]
[dalvik.vm.dex2oat-Xmx]: [512m]
[dalvik.vm.dex2oat-filter]: [verify-at-runtime]
[dalvik.vm.heapgrowthlimit]: [48m]
[dalvik.vm.heapmaxfree]: [2m]
[dalvik.vm.heapminfree]: [512k]
[dalvik.vm.heapsize]: [128m]
[dalvik.vm.heapstartsize]: [5m]
[dalvik.vm.heaptargetutilization]: [0.75]
[dalvik.vm.image-dex2oat-Xms]: [64m]
[dalvik.vm.image-dex2oat-Xmx]: [64m]
[dalvik.vm.image-dex2oat-filter]: [verify-at-runtime]
[dalvik.vm.isa.arm.features]: [default]
[dalvik.vm.isa.arm.variant]: [generic]
[dalvik.vm.lockprof.threshold]: [500]
[dalvik.vm.stack-trace-file]: [/data/anr/traces.txt]
[dalvik.vm.usejit]: [true]
[debug.atrace.tags.enableflags]: [0]
[debug.force_rtl]: [0]
[dev.bootcomplete]: [1]
[dhcp.eth0.result]: [failed]
[gsm.current.phone-type]: [1]
[gsm.network.type]: [Unknown]
[gsm.operator.alpha]: []
[gsm.operator.iso-country]: []
[gsm.operator.isroaming]: [false]
[gsm.operator.numeric]: []
[gsm.sim.operator.alpha]: []
[gsm.sim.operator.iso-country]: []
[gsm.sim.operator.numeric]: []
[gsm.sim.state]: [NOT_READY]
[hw.nobattery]: [true]
[init.svc.adbd]: [running]
[init.svc.bootanim]: [stopped]
[init.svc.console]: [running]
[init.svc.debuggerd]: [running]
[init.svc.dhcpcd_eth0]: [stopped]
[init.svc.drm]: [running]
[init.svc.gatekeeperd]: [running]
[init.svc.healthd]: [running]
[init.svc.installd]: [running]
[init.svc.keystore]: [running]
[init.svc.lmkd]: [running]
[init.svc.logd]: [running]
[init.svc.logd-reinit]: [stopped]
[init.svc.media]: [running]
[init.svc.netd]: [running]
[init.svc.perfprofd]: [running]
[init.svc.servicemanager]: [running]
[init.svc.surfaceflinger]: [running]
[init.svc.ueventd]: [running]
[init.svc.vold]: [running]
[init.svc.zygote]: [running]
[net.bt.name]: [Android]
[net.change]: [net.qtaguid_enabled]
[net.hostname]: [android-6f4322d0401fae47]
[net.qtaguid_enabled]: [0]
[net.tcp.default_init_rwnd]: [60]
[persist.sys.dalvik.vm.lib.2]: [libart.so]
[persist.sys.profiler_ms]: [0]
[persist.sys.strictmode.disable]: [1]
[persist.sys.strictmode.visual]: [0]
[persist.sys.usb.config]: [adb]
[ro.allow.mock.location]: [1]
[ro.baseband]: [unknown]
[ro.board.platform]: [omap3]
[ro.boot.console]: [ttyS0]
[ro.boot.hardware]: [am335xevm]
[ro.boot.selinux]: [permissive]
[ro.bootimage.build.date]: [Wed Mar 15 19:58:24 EDT 2017]
[ro.bootimage.build.date.utc]: [1489622304]
[ro.bootimage.build.fingerprint]: [Android/beagleboneblack_sd/beagleboneblack:6.0.1/MOB31S/jeramy03151851:eng/test-keys]
[ro.bootloader]: [unknown]
[ro.bootmode]: [unknown]
[ro.build.characteristics]: [tablet,nosdcard]
[ro.build.date]: [Wed Mar 15 19:12:01 EDT 2017]
[ro.build.date.utc]: [1489619521]
[ro.build.description]: [beagleboneblack_sd-eng 6.0.1 MOB31S eng.jeramy.20170315.184841 test-keys]
[ro.build.display.id]: [beagleboneblack_sd-eng 6.0.1 MOB31S eng.jeramy.20170315.184841 test-keys]
[ro.build.fingerprint]: [Android/beagleboneblack_sd/beagleboneblack:6.0.1/MOB31S/jeramy03151851:eng/test-keys]
[ro.build.flavor]: [beagleboneblack_sd-eng]
[ro.build.host]: [jeramy-pc2]
[ro.build.id]: [MOB31S]
[ro.build.product]: [beagleboneblack]
[ro.build.tags]: [test-keys]
[ro.build.type]: [eng]
[ro.build.user]: [jeramy]
[ro.build.version.all_codenames]: [REL]
[ro.build.version.base_os]: []
[ro.build.version.codename]: [REL]
[ro.build.version.incremental]: [eng.jeramy.20170315.184841]
[ro.build.version.preview_sdk]: [0]
[ro.build.version.release]: [6.0.1]
[ro.build.version.sdk]: [23]
[ro.build.version.security_patch]: [2017-01-05]
[ro.carrier]: [unknown]
[ro.config.alarm_alert]: [Alarm_Classic.ogg]
[ro.config.low_ram]: [true]
[ro.config.notification_sound]: [pixiedust.ogg]
[ro.config.ringtone]: [Ring_Synth_04.ogg]
[ro.crypto.state]: [unencrypted]
[ro.dalvik.vm.native.bridge]: [0]
[ro.debuggable]: [1]
[ro.hardware]: [am335xevm]
[ro.kernel.android.checkjni]: [1]
[ro.kernel.androidboot.console]: [ttyS0]
[ro.kernel.androidboot.hardware]: [am335xevm]
[ro.kernel.androidboot.selinux]: [permissive]
[ro.kernel.cape_universal]: [enable]
[ro.kernel.console]: [ttyS0,115200n8]
[ro.kernel.qemu]: [1]
[ro.kernel.qemu.gles]: [0]
[ro.kernel.security]: [selinux]
[ro.product.board]: [beagleboneblack]
[ro.product.brand]: [Android]
[ro.product.cpu.abi]: [armeabi-v7a]
[ro.product.cpu.abi2]: [armeabi]
[ro.product.cpu.abilist]: [armeabi-v7a,armeabi]
[ro.product.cpu.abilist32]: [armeabi-v7a,armeabi]
[ro.product.cpu.abilist64]: []
[ro.product.device]: [beagleboneblack]
[ro.product.locale]: [en-US]
[ro.product.manufacturer]: [BeagleBoard.org]
[ro.product.model]: [BeagleBone Black on SD card]
[ro.product.name]: [beagleboneblack_sd]
[ro.revision]: [0]
[ro.runtime.firstboot]: [946684878742]
[ro.secure]: [0]
[ro.serialno]: []
[ro.sf.lcd_density]: [160]
[ro.wifi.channels]: []
[ro.zygote]: [zygote32]
[selinux.reload_policy]: [1]
[service.bootanim.exit]: [1]
[sys.boot_completed]: [1]
[sys.sysctl.extra_free_kbytes]: [9216]
[sys.usb.config]: [adb]
[sys.usb.configfs]: [1]
[sys.usb.controller]: [musb-hdrc.0.auto]
[sys.usb.ffs.ready]: [1]
[sys.usb.state]: [adb]
[vold.has_adoptable]: [0]
[vold.post_fs_data_done]: [1]
[wlan.driver.status]: [unloaded]