--- a/a/nspr/configure
+++ a/a/nspr/configure
@@ -821,6 +821,7 @@
         linux*)       OS_ARCH=Linux ;;
         solaris*)     OS_ARCH=SunOS OS_RELEASE=5 ;;
         mingw*)       OS_ARCH=WINNT CPU_ARCH=x86 ;;
+        cygwin*)      OS_ARCH=WINNT ;;
         darwin*)      OS_ARCH=Darwin ;;
         riscos*)      OS_ARCH=RISCOS ;;
     esac
--- a/a/nss/lib/freebl/Makefile.orig
+++ a/a/nss/lib/freebl/Makefile
@@ -119,8 +119,23 @@
 endif
 endif
 ifeq ($(CPU_ARCH),aarch64)
-    DEFINES += -DUSE_HW_AES -DUSE_HW_SHA2
-    EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha256-armv8.c
+    ifdef CC_IS_CLANG
+        DEFINES += -DUSE_HW_AES -DUSE_HW_SHA2
+        EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha256-armv8.c
+    else ifeq (1,$(CC_IS_GCC))
+        # GCC versions older than 4.9 don't support ARM AES. The check
+        # is done in two parts, first allows "major.minor" == "4.9",
+        # and then rejects any major versions prior to 5. Note that
+        # there has been no GCC 4.10, as it is renamed to GCC 5.
+        ifneq (,$(filter 4.9,$(word 1,$(GCC_VERSION)).$(word 2,$(GCC_VERSION))))
+            DEFINES += -DUSE_HW_AES -DUSE_HW_SHA2
+            EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha256-armv8.c
+        endif
+        ifeq (,$(filter 0 1 2 3 4,$(word 1,$(GCC_VERSION))))
+            DEFINES += -DUSE_HW_AES -DUSE_HW_SHA2
+            EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha256-armv8.c
+        endif
+    endif
 endif
 ifeq ($(CPU_ARCH),arm)
 ifndef NSS_DISABLE_ARM32_NEON
@@ -133,7 +146,10 @@
         DEFINES += -DUSE_HW_AES -DUSE_HW_SHA2
         EXTRA_SRCS += aes-armv8.c sha256-armv8.c
     else ifeq (1,$(CC_IS_GCC))
-        # Old compiler doesn't support ARM AES.
+        # GCC versions older than 4.9 don't support ARM AES. The check
+        # is done in two parts, first allows "major.minor" == "4.9",
+        # and then rejects any major versions prior to 5. Note that
+        # there has been no GCC 4.10, as it is renamed to GCC 5.
         ifneq (,$(filter 4.9,$(word 1,$(GCC_VERSION)).$(word 2,$(GCC_VERSION))))
             DEFINES += -DUSE_HW_AES -DUSE_HW_SHA2
             EXTRA_SRCS += aes-armv8.c sha256-armv8.c
@@ -198,6 +200,7 @@
     ifdef BUILD_OPT
 	OPTIMIZER += -Ox  # maximum optimization for freebl
     endif
+ifeq ($(CPU_ARCH),x86_64)
     ASFILES  = arcfour-amd64-masm.asm mpi_amd64_masm.asm mp_comba_amd64_masm.asm
     DEFINES += -DNSS_BEVAND_ARCFOUR -DMPI_AMD64 -DMP_ASSEMBLY_MULTIPLY
     DEFINES += -DNSS_USE_COMBA
@@ -215,6 +218,7 @@
 endif
 endif
 endif
+endif
 
 ifeq ($(OS_TARGET),IRIX)
 ifeq ($(USE_N32),1)