diff --git a/aclocal.m4 b/aclocal.m4
index 20464eef535a..10b7e6a1ca46 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -7,7 +7,6 @@ builtin(include, build/autoconf/hooks.m4)dnl
 builtin(include, build/autoconf/config.status.m4)dnl
 builtin(include, build/autoconf/toolchain.m4)dnl
 builtin(include, build/autoconf/altoptions.m4)dnl
-builtin(include, build/autoconf/arch.m4)dnl
 builtin(include, build/autoconf/clang-plugin.m4)dnl
 
 # Read the user's .mozconfig script.  We can't do this in
diff --git a/build/autoconf/arch.m4 b/build/autoconf/arch.m4
deleted file mode 100644
index 2d1158875e76..000000000000
--- a/build/autoconf/arch.m4
+++ /dev/null
@@ -1,14 +0,0 @@
-dnl This Source Code Form is subject to the terms of the Mozilla Public
-dnl License, v. 2.0. If a copy of the MPL was not distributed with this
-dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-AC_DEFUN([MOZ_ARCH_OPTS],
-[
-if test -n "$_ARM_FLAGS"; then
-    CFLAGS="$CFLAGS $_ARM_FLAGS"
-    CXXFLAGS="$CXXFLAGS $_ARM_FLAGS"
-    if test -n "$_THUMB_FLAGS"; then
-        LDFLAGS="$LDFLAGS $_THUMB_FLAGS"
-    fi
-fi
-])
diff --git a/build/moz.configure/arm.configure b/build/moz.configure/arm.configure
index 5d26f4d73239..99c582748ef8 100644
--- a/build/moz.configure/arm.configure
+++ b/build/moz.configure/arm.configure
@@ -172,10 +172,6 @@ def all_arm_flags(flags, interwork):
     return flags + interwork
 
 
-add_old_configure_assignment("_ARM_FLAGS", all_arm_flags)
-add_old_configure_assignment("_THUMB_FLAGS", thumb_option)
-
-
 @depends(configure_cache, c_compiler, all_arm_flags)
 @checking("ARM version support in compiler", lambda x: x.arm_arch)
 @imports(_from="textwrap", _import="dedent")
diff --git a/build/moz.configure/flags.configure b/build/moz.configure/flags.configure
index 0c9ff0625cd2..d0c1e1b50d56 100644
--- a/build/moz.configure/flags.configure
+++ b/build/moz.configure/flags.configure
@@ -610,6 +610,32 @@ def os_cppflags(env_cppflags):
     return flags
 
 
+@depends("CFLAGS", compilation_flags, android_flags, all_arm_flags)
+@imports(_from="mozbuild.shellutil", _import="split")
+def os_cflags(env_cflags, compilation_flags, android_flags, all_arm_flags):
+    flags = []
+    if android_flags:
+        flags.extend(android_flags.cflags)
+    if all_arm_flags:
+        flags.extend(all_arm_flags)
+    flags.extend(compilation_flags.cflags)
+    flags.extend(split(env_cflags[0]))
+    return flags
+
+
+@depends("CXXFLAGS", compilation_flags, android_flags, all_arm_flags)
+@imports(_from="mozbuild.shellutil", _import="split")
+def os_cxxflags(env_cxxflags, compilation_flags, android_flags, all_arm_flags):
+    flags = []
+    if android_flags:
+        flags.extend(android_flags.cxxflags)
+    if all_arm_flags:
+        flags.extend(all_arm_flags)
+    flags.extend(compilation_flags.cxxflags)
+    flags.extend(split(env_cxxflags[0]))
+    return flags
+
+
 @depends(
     "ASFLAGS",
     asm_flags,
@@ -642,12 +668,24 @@ def os_asflags(
     return flags
 
 
-# Please keep these last in this file.
-add_old_configure_assignment("_COMPILATION_LDFLAGS", linker_flags.ldflags)
-add_old_configure_assignment("CPPFLAGS", os_cppflags)
+@depends("LDFLAGS", linker_flags, android_flags, thumb_option)
+@imports(_from="mozbuild.shellutil", _import="split")
+def os_ldflags(env_ldflags, linker_flags, android_flags, thumb_option):
+    flags = []
+    if android_flags:
+        flags.extend(android_flags.ldflags)
+    if thumb_option:
+        flags.extend(thumb_option)
+    flags.extend(split(env_ldflags[0]))
+    flags.extend(linker_flags.ldflags)
+    return flags
 
-add_old_configure_assignment("_COMPILATION_CFLAGS", compilation_flags.cflags)
-add_old_configure_assignment("_COMPILATION_CXXFLAGS", compilation_flags.cxxflags)
+
+# Please keep these last in this file.
+add_old_configure_assignment("CPPFLAGS", os_cppflags)
+add_old_configure_assignment("CFLAGS", os_cflags)
+add_old_configure_assignment("CXXFLAGS", os_cxxflags)
+add_old_configure_assignment("LDFLAGS", os_ldflags)
 
 set_config("HOST_CPPFLAGS", host_cppflags)
 set_config("HOST_CFLAGS", host_cflags)
diff --git a/build/moz.configure/toolchain.configure b/build/moz.configure/toolchain.configure
index 4c1d81c867db..cf9656cd8a38 100644
--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -46,6 +46,22 @@ option(
 )
 
 
+option(
+    env="CFLAGS",
+    help="Extra flags for compiling C sources.",
+    nargs=1,
+    default="",
+)
+
+
+option(
+    env="CXXFLAGS",
+    help="Extra flags for compiling C++ sources.",
+    nargs=1,
+    default="",
+)
+
+
 option(
     env="ASFLAGS",
     help="Extra flags for assembling sources.",
@@ -54,6 +70,14 @@ option(
 )
 
 
+option(
+    env="LDFLAGS",
+    help="Extra flags for linking object files.",
+    nargs=1,
+    default="",
+)
+
+
 option(
     env="MOZ_OPTIMIZE_FLAGS",
     help="Extra optimization flags.",
@@ -61,6 +85,7 @@ option(
     default="",
 )
 
+
 # Code optimization
 # ==============================================================
 
diff --git a/build/mozconfig.no-compile b/build/mozconfig.no-compile
index 32890d0710f5..d34e9214039e 100644
--- a/build/mozconfig.no-compile
+++ b/build/mozconfig.no-compile
@@ -9,6 +9,10 @@ NO_CACHE=1
 # Override any toolchain defines we've inherited from other mozconfigs.
 unset CC
 unset CXX
+unset CPPFLAGS
+unset CFLAGS
+unset CXXFLAGS
+unset LDFLAGS
 unset HOST_CC
 unset HOST_CXX
 unset HOST_CPPFLAGS
diff --git a/js/src/aclocal.m4 b/js/src/aclocal.m4
index ee59549d0545..cb0936d006a7 100644
--- a/js/src/aclocal.m4
+++ b/js/src/aclocal.m4
@@ -7,7 +7,6 @@ builtin(include, ../../build/autoconf/hooks.m4)dnl
 builtin(include, ../../build/autoconf/config.status.m4)dnl
 builtin(include, ../../build/autoconf/toolchain.m4)dnl
 builtin(include, ../../build/autoconf/altoptions.m4)dnl
-builtin(include, ../../build/autoconf/arch.m4)dnl
 builtin(include, ../../build/autoconf/clang-plugin.m4)dnl
 
 define([__MOZ_AC_INIT_PREPARE], defn([AC_INIT_PREPARE]))
diff --git a/js/src/old-configure.in b/js/src/old-configure.in
index 0a053654800c..8471d86ccfb5 100644
--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -11,27 +11,6 @@ AC_INIT(js/src/jsapi.h)
 AC_CONFIG_AUX_DIR(${srcdir}/build/autoconf)
 AC_CANONICAL_SYSTEM
 
-dnl ========================================================
-dnl =
-dnl = Don't change the following lines. Doing so breaks:
-dnl =
-dnl = CFLAGS="-foo" ./configure
-dnl =
-dnl ========================================================
-CFLAGS="${CFLAGS=}"
-CXXFLAGS="${CXXFLAGS=}"
-LDFLAGS="${LDFLAGS=}"
-
-dnl Propagate extra android flags
-dnl =============================
-case "$target" in
-*-android*|*-linuxandroid*)
-    LDFLAGS="$ANDROID_LDFLAGS $LDFLAGS"
-    CFLAGS="$ANDROID_CFLAGS $CFLAGS"
-    CXXFLAGS="$ANDROID_CXXFLAGS $CXXFLAGS"
-    ;;
-esac
-
 
 dnl Set the minimum version of toolkit libs used by mozilla
 dnl ========================================================
@@ -70,10 +49,6 @@ fi
 
 fi # COMPILE_ENVIRONMENT
 
-dnl Configure platform-specific CPU architecture compiler options.
-dnl ==============================================================
-MOZ_ARCH_OPTS
-
 dnl ========================================================
 dnl System overrides of the defaults for target
 dnl ========================================================
@@ -214,19 +189,6 @@ AC_SUBST(MOZ_POST_PROGRAM_COMMAND)
 
 AC_SUBST(MOZ_APP_DISPLAYNAME)
 
-dnl Echo the CFLAGS to remove extra whitespace.
-CFLAGS=`echo \
-	$_COMPILATION_CFLAGS \
-	$CFLAGS`
-
-CXXFLAGS=`echo \
-	$_COMPILATION_CXXFLAGS \
-	$CXXFLAGS`
-
-LDFLAGS=`echo \
-    $LDFLAGS \
-    $_COMPILATION_LDFLAGS`
-
 OS_CFLAGS="$CFLAGS"
 OS_CXXFLAGS="$CXXFLAGS"
 OS_LDFLAGS="$LDFLAGS"
diff --git a/old-configure.in b/old-configure.in
index 3ac5248b6316..93e0c6d19e8b 100644
--- a/old-configure.in
+++ b/old-configure.in
@@ -11,29 +11,6 @@ AC_INIT(config/config.mk)
 AC_CONFIG_AUX_DIR(${srcdir}/build/autoconf)
 AC_CANONICAL_SYSTEM
 
-dnl ========================================================
-dnl =
-dnl = Don't change the following lines. Doing so breaks:
-dnl =
-dnl = CFLAGS="-foo" ./configure
-dnl =
-dnl ========================================================
-CFLAGS="${CFLAGS=}"
-CXXFLAGS="${CXXFLAGS=}"
-LDFLAGS="${LDFLAGS=}"
-
-
-dnl Propagate extra android flags
-dnl =============================
-case "$target" in
-*-android*|*-linuxandroid*)
-    LDFLAGS="$ANDROID_LDFLAGS $LDFLAGS"
-    CFLAGS="$ANDROID_CFLAGS $CFLAGS"
-    CXXFLAGS="$ANDROID_CXXFLAGS $CXXFLAGS"
-    ;;
-esac
-
-
 dnl Set the minimum version of toolkit libs used by mozilla
 dnl ========================================================
 
@@ -64,12 +41,6 @@ fi
 
 fi # COMPILE_ENVIRONMENT
 
-dnl Configure platform-specific CPU architecture compiler options.
-dnl ==============================================================
-if test "$COMPILE_ENVIRONMENT"; then
-    MOZ_ARCH_OPTS
-fi # COMPILE_ENVIRONMENT
-
 dnl ========================================================
 dnl System overrides of the defaults for target
 dnl ========================================================
@@ -358,19 +329,6 @@ AC_DEFINE_UNQUOTED(MOZ_APP_UA_VERSION, "$MOZ_APP_VERSION")
 
 AC_SUBST(MOZ_APP_MAXVERSION)
 
-dnl Echo the CFLAGS to remove extra whitespace.
-CFLAGS=`echo \
-    $_COMPILATION_CFLAGS \
-    $CFLAGS`
-
-CXXFLAGS=`echo \
-    $_COMPILATION_CXXFLAGS \
-    $CXXFLAGS`
-
-LDFLAGS=`echo \
-    $LDFLAGS \
-    $_COMPILATION_LDFLAGS`
-
 OS_CFLAGS="$CFLAGS"
 OS_CXXFLAGS="$CXXFLAGS"
 OS_LDFLAGS="$LDFLAGS"