Make Problems with JDK 6u17 Build - makefile

Question

I'm trying to build an older version of the JDK for work, and have run into a roadblock when running make dev-sanity. Well, several roadblocks, but I've managed to get around all of them but this one. Specifically, I'm trying to build a 64-bit version of JDK 1.6u17 from the source JAR here:
Source download page
Build README
TL;DR: I'm building JDK6u17 from source and I'm getting errors in the dev-sanity target in make. I have all the software and versions thereof listed in the build readme, so I think it's an environment variable problem.
Software Version Info
Windows 7, amd64 processor
cl.exe version is 14.00.50727.762
link.exe version is 8.00.50727.762
Java bootstrap is JDK 1.7u15
msvcrt.dll version is 7.0.7601.17744
Cygwin is the current version
make is the Cygwin build of GNU make, version 3.80-1, which supports DOS paths. I've also tried versions 3.81 and 3.82 from the official repositories, which don't work because they don't have DOS path support, as well as patched 3.81 and 3.82 versions with DOS path support, which both gave me the same erroneous output as 3.80.
Environment Variables
PATH - includes the compiler tools, the bootstrap JDK, the UNIX tools from Cygwin, then everything else that was already on my path, in that order.
LIB - set as user environment variable using SetEnv.cmd /X64 in the Microsoft SDK's Bin folder to get the value
INCLUDE - set as user environment variable using SetEnv.cmd /X64 in the Microsoft SDK's Bin folder to get the value
ALT_COMPILER_PATH - set to C:\PROGRA~1\MICROS~2\Windows\v6.0\VC\Bin\x64\ (using short-path to avoid problems with spaces)
ALT_BOOTDIR - C:\PROGRA~1\Java\JDK17~1.0_1\ (JDK 7 path)
ALT_MSVCRT_DLL_PATH - C:\Windows\System32\ (the msvcrt.dll file is in my System32 folder)
ALT_DXSDK_PATH - just set to short-path of DXSDK_DIR
I'm able to open Cygwin and start the make process using:
make dev-sanity ARCH_DATA_MODEL=64 ARCH=amd64
But then it errors out with the following output:
$ cd [jdk-src-root]/control/make
$ make dev-sanity ARCH_DATA_MODEL=64 ARCH=amd64
cd ../../control/make
make sanity DEV_ONLY=true
make[1]: Entering directory `/cygdrive/c/Users/bsaltz/jdk6u17src/control/make'
make[2]: Entering directory `/cygdrive/c/Users/bsaltz/jdk6u17src/deploy/make'
../make/common/Defs.gmk:52: /make/common/Defs.gmk: No such file or directory
make[2]: -p: Command not found
make[2]: -p: Command not found
../make/common/Defs-windows.gmk:9: /make/common/Defs-windows.gmk: No such file or directory
../../j2se/make/common/Defs-windows.gmk:16: /Defs.gmk: No such file or directory
/bin/sh: - : invalid option
Usage: /bin/sh [GNU long option] [option] ...
/bin/sh [GNU long option] [option] script-file ...
[ ... More /bin/sh usage output ]
/bin/sh: - : invalid option
Usage: /bin/sh [GNU long option] [option] ...
/bin/sh [GNU long option] [option] script-file ...
[ ... More /bin/sh usage output ]
/bin/sh: #define: command not found
/bin/sh: {print $3}: command not found
/bin/sh: -n: command not found
/bin/sh: - : invalid option
/bin/sh: - : invalid option
/bin/sh: -n: command not found
../../j2se/make/common/shared/Sanity.gmk:97: /Sanity-Settings.gmk: No such file or directory
make[2]: -p: Command not found
make[2]: *** No rule to make target `/Sanity-Settings.gmk'. Stop.
make[2]: Leaving directory `/cygdrive/c/Users/bsaltz/jdk6u17src/deploy/make'
make[1]: *** [deploy-sanity] Error 2
make[1]: Leaving directory `/cygdrive/c/Users/bsaltz/jdk6u17src/control/make'
make: *** [dev-sanity] Error 2
From what I can make out, it looks like I might have a bad or missing environment variable somewhere since it looks like commands aren't executing properly, maybe some variables aren't being resolved.
Note that we're doing this to get debug jars with local variables, and it seems that the fastdebug jars are no longer available for 6u17. If anyone has a 6u17 fastdebug link, I'll take that too if it means I don't have to compile anything.
If anyone wants the -d output, let me know and I'll stick it on pastebin or something.