diff -ur misc/nss-3.39/nspr/configure misc/build/nss-3.39/nspr/configure
--- misc/nss-3.39/nspr/configure	2018-08-28 05:42:28.000000000 -0700
+++ misc/build/nss-3.39/nspr/configure	2020-10-06 07:41:59.563345390 -0700
@@ -6570,8 +6570,14 @@
     AS='$(CC) -x assembler-with-cpp'
     CFLAGS="$CFLAGS -Wall -fno-common"
     case "${target_cpu}" in
+        aarch64|arm64)
+            CPU_ARCH=arm64
+            ;;
         arm*)
-            CPU_ARCH=arm
+            # On Apple Silicon the bundled config.guess reports the bare CPU
+            # "arm"; the macOS arch name is "arm64" (plain "arm" makes ld pick
+            # the nonexistent armv4t).  Treat any arm on Darwin as arm64.
+            CPU_ARCH=arm64
             ;;
         i*86*|x86_64)
             if test -n "$USE_64"; then
diff -ur misc/nss-3.39/nss/lib/sqlite/config.mk misc/build/nss-3.39/nss/lib/sqlite/config.mk
--- misc/nss-3.39/nss/lib/sqlite/config.mk	2018-08-31 05:55:53.000000000 -0700
+++ misc/build/nss-3.39/nss/lib/sqlite/config.mk	2018-09-10 10:36:01.074375000 -0700
@@ -35,9 +35,9 @@
 # OSAtomicCompareAndSwapPtrBarrier, which is only available on Mac OS X 10.5
 # (Darwin 9.0) and later. Define SQLITE_WITHOUT_ZONEMALLOC to disable
 # that code for older versions of Mac OS X. See bug 820374.
-DARWIN_VER_MAJOR := $(shell uname -r | cut -f1 -d.)
-DARWIN_LT_9 := $(shell [ $(DARWIN_VER_MAJOR) -lt 9 ] && echo true)
-ifeq ($(DARWIN_LT_9),true)
+OSX_TARGET_MINOR := $(shell echo $(MACOSX_DEPLOYMENT_TARGET) | cut -f2 -d.)
+OSX_MINOR_LT_5 := $(shell [ $(OSX_TARGET_MINOR) -lt 5 ] && echo true)
+ifeq ($(OSX_MINOR_LT_5),true)
 OS_CFLAGS += -DSQLITE_WITHOUT_ZONEMALLOC
 endif
 endif # Darwin