diff --git a/config/config.mk b/config/config.mk
index c46b3b123f33..af01015dbdcf 100644
--- a/config/config.mk
+++ b/config/config.mk
@@ -634,6 +634,11 @@ PWD := $(CURDIR)
 endif
 
 NSINSTALL_PY := $(PYTHON) $(call core_abspath,$(topsrcdir)/config/nsinstall.py)
+# For Pymake, wherever we use nsinstall.py we're also going to try to make it
+# a native command where possible. Since native commands can't be used outside
+# of single-line commands, we continue to provide INSTALL for general use.
+# Single-line commands should be switched over to install_cmd.
+NSINSTALL_NATIVECMD := %nsinstall nsinstall
 
 ifdef NSINSTALL_BIN
 NSINSTALL = $(NSINSTALL_BIN)
@@ -651,7 +656,11 @@ endif # NSINSTALL_BIN
 
 
 ifeq (,$(CROSS_COMPILE)$(filter-out WINNT OS2, $(OS_ARCH)))
-INSTALL		= $(NSINSTALL) -t
+INSTALL = $(NSINSTALL) -t
+ifdef .PYMAKE
+install_cmd = $(NSINSTALL_NATIVECMD) -t $(1)
+endif # .PYMAKE
+
 else
 
 # This isn't laid out as conditional directives so that NSDISTMODE can be
@@ -660,11 +669,17 @@ INSTALL         = $(if $(filter copy, $(NSDISTMODE)), $(NSINSTALL) -t, $(if $(fi
 
 endif # WINNT/OS2
 
+# The default for install_cmd is simply INSTALL
+install_cmd ?= $(INSTALL) $(1)
+
 # Use nsinstall in copy mode to install files on the system
 SYSINSTALL	= $(NSINSTALL) -t
+# This isn't necessarily true, just here
+sysinstall_cmd = install_cmd
 
 # Directory nsinstall.
 DIR_INSTALL = $(INSTALL)
+dir_install_cmd = install_cmd
 
 #
 # Localization build automation
diff --git a/config/makefiles/xpidl.mk b/config/makefiles/xpidl.mk
index a5b8f26b59af..ba10306e181a 100644
--- a/config/makefiles/xpidl.mk
+++ b/config/makefiles/xpidl.mk
@@ -46,13 +46,13 @@ xpidl-install-src-preqs=\
   $(NULL)
 
 xpidl-install-src: $(xpidl-install-src-preqs)
-	$(INSTALL) $(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val)))
+	$(call install_cmd,$(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val))))
 
 xpidl-install-headers-preqs =\
   $(patsubst %.idl,$(XPIDL_GEN_DIR)/%.h, $(XPIDLSRCS)) \
   $(call mkdir_deps,$(DIST)/include) \
   $(NULL)
 xpidl-install-headers: $(xpidl-install-headers-preqs)
-	$(INSTALL) $(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val)))
+	$(call install_cmd,$(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val))))
 
 endif #} _xpidl-todo_
diff --git a/config/nsinstall.py b/config/nsinstall.py
index 42f920feb634..ad51c36fe534 100755
--- a/config/nsinstall.py
+++ b/config/nsinstall.py
@@ -17,7 +17,7 @@ import sys
 import shutil
 import stat
 
-def nsinstall(argv):
+def _nsinstall_internal(argv):
   usage = "usage: %prog [options] arg1 [arg2 ...] target-directory"
   p = OptionParser(usage=usage)
 
@@ -52,13 +52,6 @@ def nsinstall(argv):
                help="Set group (NOT SUPPORTED)", metavar="group")
 
   (options, args) = p.parse_args(argv)
-  # Switching to Unicode strings makes python use the wide Windows APIs, which is
-  # what we want here since the wide APIs normally do a better job at handling long
-  # paths and such.
-  if sys.stdin.encoding is None:
-    args = [unicode(arg) for arg in args]
-  else:
-    args = [unicode(arg, sys.stdin.encoding) for arg in args]
 
   if options.m:
     # mode is specified
@@ -152,9 +145,16 @@ def nsinstall(argv):
   copy_all_entries(args, target)
   return 0
 
+# nsinstall as a native command is always UTF-8
+def nsinstall(argv):
+  return _nsinstall_internal([unicode(arg, "utf-8") for arg in argv])
+
 if __name__ == '__main__':
   # sys.argv corrupts characters outside the system code page on Windows
-  # <http://bugs.python.org/issue2128>. Use ctypes instead.
+  # <http://bugs.python.org/issue2128>. Use ctypes instead. This is also
+  # useful because switching to Unicode strings makes python use the wide
+  # Windows APIs, which is what we want here since the wide APIs normally do a
+  # better job at handling long paths and such.
   if sys.platform == "win32":
     import ctypes
     from ctypes import wintypes
@@ -168,9 +168,13 @@ if __name__ == '__main__':
 
     argc = ctypes.c_int(0)
     argv_arr = CommandLineToArgv(GetCommandLine(), ctypes.byref(argc))
-    # The first argument will be "python", the second will be the .py file
+    # The first argv will be "python", the second will be the .py file
     argv = argv_arr[1:argc.value]
   else:
-    argv = sys.argv
+    # For consistency, do it on Unix as well
+    if sys.stdin.encoding is not None:
+      argv = [unicode(arg, sys.stdin.encoding) for arg in sys.argv]
+    else:
+      argv = [unicode(arg) for arg in sys.argv]
 
-  sys.exit(nsinstall(argv[1:]))
+  sys.exit(_nsinstall_internal(argv[1:]))
diff --git a/config/rules.mk b/config/rules.mk
index c9e8099cbdc4..33f3cd753a50 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -1190,14 +1190,14 @@ endif
 ifndef NO_DIST_INSTALL
 ifneq (,$(EXPORTS))
 export:: $(EXPORTS)
-	$(INSTALL) $(IFLAGS1) $^ $(DIST)/include
+	$(call install_cmd,$(IFLAGS1) $^ $(DIST)/include)
 endif
 endif # NO_DIST_INSTALL
 
 define EXPORT_NAMESPACE_RULE
 ifndef NO_DIST_INSTALL
 export:: $(EXPORTS_$(namespace))
-	$(INSTALL) $(IFLAGS1) $$^ $(DIST)/include/$(namespace)
+	$(call install_cmd,$(IFLAGS1) $$^ $(DIST)/include/$(namespace))
 endif # NO_DIST_INSTALL
 endef
 
@@ -1246,7 +1246,7 @@ $(FINAL_TARGET)/defaults/autoconfig::
 
 ifndef NO_DIST_INSTALL
 export:: $(AUTOCFG_JS_EXPORTS) $(FINAL_TARGET)/defaults/autoconfig
-	$(INSTALL) $(IFLAGS1) $^
+	$(call install_cmd,$(IFLAGS1) $^)
 endif
 
 endif
@@ -1312,7 +1312,7 @@ endif # XPIDL_MODULE.xpt != XPIDLSRCS
 
 libs:: $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS1) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(FINAL_TARGET)/components
+	$(call install_cmd,$(IFLAGS1) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(FINAL_TARGET)/components)
 ifndef NO_INTERFACES_MANIFEST
 	@$(PYTHON) $(MOZILLA_DIR)/config/buildlist.py $(FINAL_TARGET)/components/interfaces.manifest "interfaces $(XPIDL_MODULE).xpt"
 	@$(PYTHON) $(MOZILLA_DIR)/config/buildlist.py $(FINAL_TARGET)/chrome.manifest "manifest components/interfaces.manifest"
@@ -1340,7 +1340,7 @@ export-idl:: $(SUBMAKEFILES) $(MAKE_DIRS)
 ifneq ($(XPIDLSRCS),)
 ifndef NO_DIST_INSTALL
 export-idl:: $(XPIDLSRCS) $(IDL_DIR)
-	$(INSTALL) $(IFLAGS1) $^
+	$(call install_cmd,$(IFLAGS1) $^)
 endif
 endif
 	$(LOOP_OVER_PARALLEL_DIRS)
@@ -1360,7 +1360,7 @@ endif
 ifdef EXTRA_COMPONENTS
 libs:: $(EXTRA_COMPONENTS)
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS1) $^ $(FINAL_TARGET)/components
+	$(call install_cmd,$(IFLAGS1) $^ $(FINAL_TARGET)/components)
 endif
 
 endif
@@ -1390,7 +1390,7 @@ endif
 ifdef EXTRA_JS_MODULES
 libs:: $(EXTRA_JS_MODULES)
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS1) $^ $(FINAL_TARGET)/modules
+	$(call install_cmd,$(IFLAGS1) $^ $(FINAL_TARGET)/modules)
 endif
 
 endif
@@ -1423,7 +1423,7 @@ GENERATED_DIRS += $(testmodulesdir)
 
 libs:: $(TESTING_JS_MODULES)
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS) $^ $(testmodulesdir)
+	$(call install_cmd,$(IFLAGS) $^ $(testmodulesdir))
 endif
 
 endif
@@ -1437,7 +1437,7 @@ $(SDK_LIB_DIR)::
 
 ifndef NO_DIST_INSTALL
 libs:: $(SDK_LIBRARY) $(SDK_LIB_DIR)
-	$(INSTALL) $(IFLAGS2) $^
+	$(call install_cmd,$(IFLAGS2) $^)
 endif
 
 endif # SDK_LIBRARY
@@ -1448,7 +1448,7 @@ $(SDK_BIN_DIR)::
 
 ifndef NO_DIST_INSTALL
 libs:: $(SDK_BINARY) $(SDK_BIN_DIR)
-	$(INSTALL) $(IFLAGS2) $^
+	$(call install_cmd,$(IFLAGS2) $^)
 endif
 
 endif # SDK_BINARY
diff --git a/config/tests/unit-nsinstall.py b/config/tests/unit-nsinstall.py
index 3b24eab062eb..2f129e9fe871 100644
--- a/config/tests/unit-nsinstall.py
+++ b/config/tests/unit-nsinstall.py
@@ -137,8 +137,7 @@ class TestNsinstall(unittest.TestCase):
         self.assertEqual(nsinstall(["-d", testfile, destdir]), 0)
         self.assert_(os.path.isdir(os.path.join(destdir, "testfile")))
 
-    # Disable this temporarily on Windows (will be re-enabled by bug 680636)
-    if RUN_NON_ASCII_TESTS and sys.platform != "win32":
+    if RUN_NON_ASCII_TESTS:
         def test_nsinstall_non_ascii(self):
             "Test that nsinstall handles non-ASCII files"
             filename = u"\u2325\u3452\u2415\u5081"
@@ -150,7 +149,6 @@ class TestNsinstall(unittest.TestCase):
             destfile = os.path.join(testdir, filename)
             self.assert_(os.path.isfile(destfile))
 
-    if RUN_NON_ASCII_TESTS:
         def test_nsinstall_non_ascii_subprocess(self):
             "Test that nsinstall as a subprocess handles non-ASCII files"
             filename = u"\u2325\u3452\u2415\u5081"
diff --git a/js/src/config/config.mk b/js/src/config/config.mk
index c46b3b123f33..af01015dbdcf 100644
--- a/js/src/config/config.mk
+++ b/js/src/config/config.mk
@@ -634,6 +634,11 @@ PWD := $(CURDIR)
 endif
 
 NSINSTALL_PY := $(PYTHON) $(call core_abspath,$(topsrcdir)/config/nsinstall.py)
+# For Pymake, wherever we use nsinstall.py we're also going to try to make it
+# a native command where possible. Since native commands can't be used outside
+# of single-line commands, we continue to provide INSTALL for general use.
+# Single-line commands should be switched over to install_cmd.
+NSINSTALL_NATIVECMD := %nsinstall nsinstall
 
 ifdef NSINSTALL_BIN
 NSINSTALL = $(NSINSTALL_BIN)
@@ -651,7 +656,11 @@ endif # NSINSTALL_BIN
 
 
 ifeq (,$(CROSS_COMPILE)$(filter-out WINNT OS2, $(OS_ARCH)))
-INSTALL		= $(NSINSTALL) -t
+INSTALL = $(NSINSTALL) -t
+ifdef .PYMAKE
+install_cmd = $(NSINSTALL_NATIVECMD) -t $(1)
+endif # .PYMAKE
+
 else
 
 # This isn't laid out as conditional directives so that NSDISTMODE can be
@@ -660,11 +669,17 @@ INSTALL         = $(if $(filter copy, $(NSDISTMODE)), $(NSINSTALL) -t, $(if $(fi
 
 endif # WINNT/OS2
 
+# The default for install_cmd is simply INSTALL
+install_cmd ?= $(INSTALL) $(1)
+
 # Use nsinstall in copy mode to install files on the system
 SYSINSTALL	= $(NSINSTALL) -t
+# This isn't necessarily true, just here
+sysinstall_cmd = install_cmd
 
 # Directory nsinstall.
 DIR_INSTALL = $(INSTALL)
+dir_install_cmd = install_cmd
 
 #
 # Localization build automation
diff --git a/js/src/config/makefiles/xpidl.mk b/js/src/config/makefiles/xpidl.mk
index a5b8f26b59af..ba10306e181a 100644
--- a/js/src/config/makefiles/xpidl.mk
+++ b/js/src/config/makefiles/xpidl.mk
@@ -46,13 +46,13 @@ xpidl-install-src-preqs=\
   $(NULL)
 
 xpidl-install-src: $(xpidl-install-src-preqs)
-	$(INSTALL) $(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val)))
+	$(call install_cmd,$(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val))))
 
 xpidl-install-headers-preqs =\
   $(patsubst %.idl,$(XPIDL_GEN_DIR)/%.h, $(XPIDLSRCS)) \
   $(call mkdir_deps,$(DIST)/include) \
   $(NULL)
 xpidl-install-headers: $(xpidl-install-headers-preqs)
-	$(INSTALL) $(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val)))
+	$(call install_cmd,$(IFLAGS1) $(foreach val,$^,$(call mkdir_stem,$(val))))
 
 endif #} _xpidl-todo_
diff --git a/js/src/config/nsinstall.py b/js/src/config/nsinstall.py
index 42f920feb634..ad51c36fe534 100644
--- a/js/src/config/nsinstall.py
+++ b/js/src/config/nsinstall.py
@@ -17,7 +17,7 @@ import sys
 import shutil
 import stat
 
-def nsinstall(argv):
+def _nsinstall_internal(argv):
   usage = "usage: %prog [options] arg1 [arg2 ...] target-directory"
   p = OptionParser(usage=usage)
 
@@ -52,13 +52,6 @@ def nsinstall(argv):
                help="Set group (NOT SUPPORTED)", metavar="group")
 
   (options, args) = p.parse_args(argv)
-  # Switching to Unicode strings makes python use the wide Windows APIs, which is
-  # what we want here since the wide APIs normally do a better job at handling long
-  # paths and such.
-  if sys.stdin.encoding is None:
-    args = [unicode(arg) for arg in args]
-  else:
-    args = [unicode(arg, sys.stdin.encoding) for arg in args]
 
   if options.m:
     # mode is specified
@@ -152,9 +145,16 @@ def nsinstall(argv):
   copy_all_entries(args, target)
   return 0
 
+# nsinstall as a native command is always UTF-8
+def nsinstall(argv):
+  return _nsinstall_internal([unicode(arg, "utf-8") for arg in argv])
+
 if __name__ == '__main__':
   # sys.argv corrupts characters outside the system code page on Windows
-  # <http://bugs.python.org/issue2128>. Use ctypes instead.
+  # <http://bugs.python.org/issue2128>. Use ctypes instead. This is also
+  # useful because switching to Unicode strings makes python use the wide
+  # Windows APIs, which is what we want here since the wide APIs normally do a
+  # better job at handling long paths and such.
   if sys.platform == "win32":
     import ctypes
     from ctypes import wintypes
@@ -168,9 +168,13 @@ if __name__ == '__main__':
 
     argc = ctypes.c_int(0)
     argv_arr = CommandLineToArgv(GetCommandLine(), ctypes.byref(argc))
-    # The first argument will be "python", the second will be the .py file
+    # The first argv will be "python", the second will be the .py file
     argv = argv_arr[1:argc.value]
   else:
-    argv = sys.argv
+    # For consistency, do it on Unix as well
+    if sys.stdin.encoding is not None:
+      argv = [unicode(arg, sys.stdin.encoding) for arg in sys.argv]
+    else:
+      argv = [unicode(arg) for arg in sys.argv]
 
-  sys.exit(nsinstall(argv[1:]))
+  sys.exit(_nsinstall_internal(argv[1:]))
diff --git a/js/src/config/rules.mk b/js/src/config/rules.mk
index c9e8099cbdc4..33f3cd753a50 100644
--- a/js/src/config/rules.mk
+++ b/js/src/config/rules.mk
@@ -1190,14 +1190,14 @@ endif
 ifndef NO_DIST_INSTALL
 ifneq (,$(EXPORTS))
 export:: $(EXPORTS)
-	$(INSTALL) $(IFLAGS1) $^ $(DIST)/include
+	$(call install_cmd,$(IFLAGS1) $^ $(DIST)/include)
 endif
 endif # NO_DIST_INSTALL
 
 define EXPORT_NAMESPACE_RULE
 ifndef NO_DIST_INSTALL
 export:: $(EXPORTS_$(namespace))
-	$(INSTALL) $(IFLAGS1) $$^ $(DIST)/include/$(namespace)
+	$(call install_cmd,$(IFLAGS1) $$^ $(DIST)/include/$(namespace))
 endif # NO_DIST_INSTALL
 endef
 
@@ -1246,7 +1246,7 @@ $(FINAL_TARGET)/defaults/autoconfig::
 
 ifndef NO_DIST_INSTALL
 export:: $(AUTOCFG_JS_EXPORTS) $(FINAL_TARGET)/defaults/autoconfig
-	$(INSTALL) $(IFLAGS1) $^
+	$(call install_cmd,$(IFLAGS1) $^)
 endif
 
 endif
@@ -1312,7 +1312,7 @@ endif # XPIDL_MODULE.xpt != XPIDLSRCS
 
 libs:: $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS1) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(FINAL_TARGET)/components
+	$(call install_cmd,$(IFLAGS1) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(FINAL_TARGET)/components)
 ifndef NO_INTERFACES_MANIFEST
 	@$(PYTHON) $(MOZILLA_DIR)/config/buildlist.py $(FINAL_TARGET)/components/interfaces.manifest "interfaces $(XPIDL_MODULE).xpt"
 	@$(PYTHON) $(MOZILLA_DIR)/config/buildlist.py $(FINAL_TARGET)/chrome.manifest "manifest components/interfaces.manifest"
@@ -1340,7 +1340,7 @@ export-idl:: $(SUBMAKEFILES) $(MAKE_DIRS)
 ifneq ($(XPIDLSRCS),)
 ifndef NO_DIST_INSTALL
 export-idl:: $(XPIDLSRCS) $(IDL_DIR)
-	$(INSTALL) $(IFLAGS1) $^
+	$(call install_cmd,$(IFLAGS1) $^)
 endif
 endif
 	$(LOOP_OVER_PARALLEL_DIRS)
@@ -1360,7 +1360,7 @@ endif
 ifdef EXTRA_COMPONENTS
 libs:: $(EXTRA_COMPONENTS)
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS1) $^ $(FINAL_TARGET)/components
+	$(call install_cmd,$(IFLAGS1) $^ $(FINAL_TARGET)/components)
 endif
 
 endif
@@ -1390,7 +1390,7 @@ endif
 ifdef EXTRA_JS_MODULES
 libs:: $(EXTRA_JS_MODULES)
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS1) $^ $(FINAL_TARGET)/modules
+	$(call install_cmd,$(IFLAGS1) $^ $(FINAL_TARGET)/modules)
 endif
 
 endif
@@ -1423,7 +1423,7 @@ GENERATED_DIRS += $(testmodulesdir)
 
 libs:: $(TESTING_JS_MODULES)
 ifndef NO_DIST_INSTALL
-	$(INSTALL) $(IFLAGS) $^ $(testmodulesdir)
+	$(call install_cmd,$(IFLAGS) $^ $(testmodulesdir))
 endif
 
 endif
@@ -1437,7 +1437,7 @@ $(SDK_LIB_DIR)::
 
 ifndef NO_DIST_INSTALL
 libs:: $(SDK_LIBRARY) $(SDK_LIB_DIR)
-	$(INSTALL) $(IFLAGS2) $^
+	$(call install_cmd,$(IFLAGS2) $^)
 endif
 
 endif # SDK_LIBRARY
@@ -1448,7 +1448,7 @@ $(SDK_BIN_DIR)::
 
 ifndef NO_DIST_INSTALL
 libs:: $(SDK_BINARY) $(SDK_BIN_DIR)
-	$(INSTALL) $(IFLAGS2) $^
+	$(call install_cmd,$(IFLAGS2) $^)
 endif
 
 endif # SDK_BINARY