--- a/old-configure.in
+++ b/old-configure.in
@@ -933,17 +933,17 @@ case "$target" in
 
         WIN32_CONSOLE_EXE_LDFLAGS=-mconsole
         WIN32_GUI_EXE_LDFLAGS=-mwindows
 
         # GCC/binutils can't link to a function if we try to include dllexport function
         # in the same library as dllimport caller. To work around it, we build NSPR
         # and NSS with -mnop-fun-dllimport flag. The drawback of this solution is that
         # function thunks need to be generated for cross-DLL calls.
-        MOZ_FOLD_LIBS_FLAGS=-mnop-fun-dllimport
+        MOZ_FOLD_LIBS_FLAGS="-mnop-fun-dllimport"
     else
         TARGET_COMPILER_ABI=msvc
         if test "$AS_BIN"; then
             AS="$(basename "$AS_BIN")"
         fi
         AR='lib'
         AR_FLAGS='-NOLOGO -OUT:$@'
         AR_EXTRACT=
@@ -5361,17 +5361,17 @@ AC_SUBST(MOZ_CODE_COVERAGE)
 AC_SUBST(LIBJPEG_TURBO_USE_YASM)
 AC_SUBST_LIST(LIBJPEG_TURBO_ASFLAGS)
 AC_SUBST(MOZ_LIBAV_FFT)
 AC_SUBST_LIST(LIBAV_FFT_ASFLAGS)
 AC_SUBST(MOZ_DEVTOOLS)
 
 AC_SUBST(MOZ_PACKAGE_JSSHELL)
 AC_SUBST(MOZ_FOLD_LIBS)
-AC_SUBST(MOZ_FOLD_LIBS_FLAGS)
+AC_SUBST_LIST(MOZ_FOLD_LIBS_FLAGS)
 AC_SUBST(SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE)
 
 AC_SUBST(DMG_TOOL)
 
 dnl Host JavaScript runtime, if any, to use during cross compiles.
 AC_SUBST(JS_BINARY)
 
 AC_SUBST(NSS_EXTRA_SYMBOLS_FILE)

--- a/security/generate_mapfile.py
+++ b/security/generate_mapfile.py
@@ -7,43 +7,49 @@
 # This script processes NSS .def files according to the rules defined in
 # a comment at the top of each one. The files are used to define the
 # exports from NSS shared libraries, with -DEFFILE on Windows, a linker
 # script on Linux, or with -exported_symbols_list on OS X.
 #
 # The NSS build system processes them using a series of sed replacements,
 # but the Mozilla build system is already running a Python script to generate
 # the file so it's simpler to just do the replacement in Python.
+#
+# One difference between the NSS build system and Mozilla's is that
+# Mozilla's supports building on Linux for Windows using MinGW. MinGW
+# expects all lines containing ;+ removed and all ;- tokens removed.
 
 import buildconfig
 
 
 def main(output, input):
     is_darwin = buildconfig.substs['OS_ARCH'] == 'Darwin'
+    is_mingw = "WINNT" == buildconfig.substs['OS_ARCH'] and buildconfig.substs['GCC_USE_GNU_LD']
 
     with open(input, 'rb') as f:
         for line in f:
             line = line.rstrip()
-            # Remove all lines containing ';-'
-            if ';-' in line:
+            # On everything except MinGW, remove all lines containing ';-'
+            if not is_mingw and ';-' in line:
                 continue
             # On OS X, remove all lines containing ';+'
             if is_darwin and ';+' in line:
                 continue
             # Remove the string ' DATA '.
             line = line.replace(' DATA ', '')
             # Remove the string ';+'
-            line = line.replace(';+', '')
+            if not is_mingw:
+                line = line.replace(';+', '')
             # Remove the string ';;'
             line = line.replace(';;', '')
             # If a ';' is present, remove everything after it,
             # and on OS X, remove it as well.
             i = line.find(';')
             if i != -1:
-                if is_darwin:
+                if is_darwin or is_mingw:
                     line = line[:i]
                 else:
                     line = line[:i+1]
             # On OS X, symbols get an underscore in front.
             if line and is_darwin:
                 output.write('_')
             output.write(line)
             output.write('\n')

--- a/security/moz.build
+++ b/security/moz.build
@@ -88,16 +88,18 @@ else:
     gyp_vars['nspr_include_dir'] = CONFIG['NSPR_INCLUDE_DIR']
     gyp_vars['nspr_lib_dir'] = CONFIG['NSPR_LIB_DIR']
     # The Python scripts that detect clang need it to be set as CC
     # in the environment, which isn't true here. I don't know that
     # setting that would be harmful, but we already have this information
     # anyway.
     if CONFIG['CLANG_CXX'] or CONFIG['CLANG_CL']:
         gyp_vars['cc_is_clang'] = 1
+    if CONFIG['GCC_USE_GNU_LD']:
+        gyp_vars['cc_use_gnu_ld'] = 1
 
     GYP_DIRS += ['nss']
     GYP_DIRS['nss'].input = 'nss/nss.gyp'
     GYP_DIRS['nss'].variables = gyp_vars
 
     sandbox_vars = {
         # NSS explicitly exports its public symbols
         # with linker scripts.
@@ -108,16 +110,18 @@ else:
         # We could probably do so, but not without a lot of
         # careful consideration.
         'NO_PGO': True,
     }
     if CONFIG['OS_TARGET'] == 'WINNT':
         if CONFIG['CPU_ARCH'] == 'x86':
             # This should really be the default.
             sandbox_vars['ASFLAGS'] = ['-safeseh']
+        if CONFIG['MOZ_FOLD_LIBS_FLAGS']:
+            sandbox_vars['CFLAGS'] = CONFIG['MOZ_FOLD_LIBS_FLAGS']
     if CONFIG['OS_TARGET'] == 'Android':
         sandbox_vars['CFLAGS'] = [
             '-include', TOPSRCDIR + '/security/manager/android_stub.h',
             # Setting sandbox_vars['DEFINES'] is broken currently.
             '-DCHECK_FORK_GETPID',
         ]
         if CONFIG['ANDROID_VERSION']:
             sandbox_vars['CFLAGS'] += ['-DANDROID_VERSION=' + CONFIG['ANDROID_VERSION']]