diff --git a/config/config.mk b/config/config.mk
index 201fdafa5a3..515f6f760fa 100644
--- a/config/config.mk
+++ b/config/config.mk
@@ -349,6 +349,7 @@ CFLAGS		+= $(MOZ_OPTIMIZE_FLAGS)
 CXXFLAGS	+= $(MOZ_OPTIMIZE_FLAGS)
 endif # MOZ_OPTIMIZE == 1
 LDFLAGS		+= $(MOZ_OPTIMIZE_LDFLAGS)
+RUSTFLAGS	+= $(MOZ_OPTIMIZE_RUSTFLAGS)
 endif # MOZ_OPTIMIZE
 
 ifdef CROSS_COMPILE
diff --git a/config/rules.mk b/config/rules.mk
index d924c7b4124..3d7e454aa9b 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -888,7 +888,8 @@ $(basename $2$(notdir $1)).$(OBJ_SUFFIX): $1 $$(call mkdir_deps,$$(MDDEPDIR))
 endef
 $(foreach f,$(CSRCS) $(SSRCS) $(CPPSRCS) $(CMSRCS) $(CMMSRCS) $(ASFILES),$(eval $(call src_objdep,$(f))))
 $(foreach f,$(HOST_CSRCS) $(HOST_CPPSRCS) $(HOST_CMSRCS) $(HOST_CMMSRCS),$(eval $(call src_objdep,$(f),host_)))
-# The rust compiler only outputs library objects, and so we need different
+
+# The Rust compiler only outputs library objects, and so we need different
 # mangling to generate dependency rules for it.
 mk_libname = $(basename lib$(notdir $1)).$(LIB_SUFFIX)
 src_libdep = $(call mk_libname,$1): $1 $$(call mkdir_deps,$$(MDDEPDIR))
@@ -946,7 +947,7 @@ ifdef MOZ_RUST
 # in the target's LIBS.
 $(RSOBJS):
 	$(REPORT_BUILD)
-	$(RUSTC) --crate-type staticlib -o $(call mk_libname,$<) $(_VPATH_SRCS)
+	$(RUSTC) $(RUSTFLAGS) --crate-type staticlib -o $(call mk_libname,$<) $(_VPATH_SRCS)
 endif
 
 $(SOBJS):
diff --git a/configure.in b/configure.in
index 02787e347a2..b92c11a4a8b 100644
--- a/configure.in
+++ b/configure.in
@@ -29,6 +29,7 @@ LDFLAGS="${LDFLAGS=}"
 HOST_CFLAGS="${HOST_CFLAGS=}"
 HOST_CXXFLAGS="${HOST_CXXFLAGS=}"
 HOST_LDFLAGS="${HOST_LDFLAGS=}"
+RUSTFLAGS="${RUSTFLAGS=}"
 
 dnl ========================================================
 dnl = Preserve certain environment flags passed to configure
@@ -429,7 +430,7 @@ if test -n "$RUSTC"; then
   AC_MSG_RESULT([$RUSTC_VERSION (v${_RUSTC_MAJOR_VERSION}.${_RUSTC_MINOR_VERSION}.${_RUSTC_PATCH_VERSION})])
 fi
 MOZ_ARG_ENABLE_BOOL([rust],
-                    [  --enable-rust           Include rust language sources],
+                    [  --enable-rust           Include Rust language sources],
                     [MOZ_RUST=1],
                     [MOZ_RUST= ])
 if test -z "$RUSTC" -a -n "$MOZ_RUST"; then
@@ -440,7 +441,7 @@ fi
 if test -n "$MOZ_RUST" && test -z "$_RUSTC_MAJOR_VERSION" -o \
   "$_RUSTC_MAJOR_VERSION" -lt 1; then
   AC_MSG_ERROR([Rust compiler ${RUSTC_VERSION} is too old.
-    To compile rust language sources please install at least
+    To compile Rust language sources please install at least
     version 1.0 of the 'rustc' toolchain and make sure it is
     first in your path.
     You can verify this by typing 'rustc --version'.])
@@ -505,7 +506,7 @@ EOF
   if test -z "$MOZ_RUST"; then
     AC_MSG_ERROR([rustc does not support MacOS X $MACOSX_DEPLOYMENT_TARGET
       Add 'ac_add_options --enable-macos-target=10.7' (or later)
-      to mozconfig, disable rust support, or use an alternate toolchain.])
+      to mozconfig, disable Rust support, or use an alternate toolchain.])
   fi
 fi
 
@@ -7054,6 +7055,10 @@ if test -z "$MOZ_OPTIMIZE_FLAGS"; then
     MOZ_OPTIMIZE_FLAGS="-O"
 fi
 
+if test -z "$MOZ_OPTIMIZE_RUSTFLAGS"; then
+    MOZ_OPTIMIZE_RUSTFLAGS="-O"
+fi
+
 MOZ_ARG_ENABLE_STRING(optimize,
 [  --disable-optimize      Disable compiler optimization
   --enable-optimize=[OPT] Specify compiler optimization flags [OPT=-O]],
@@ -7071,7 +7076,7 @@ MOZ_SET_FRAMEPTR_FLAGS
 
 if test "$COMPILE_ENVIRONMENT"; then
 if test -n "$MOZ_OPTIMIZE"; then
-    AC_MSG_CHECKING([for valid optimization flags])
+    AC_MSG_CHECKING([for valid C compiler optimization flags])
     _SAVE_CFLAGS=$CFLAGS
     CFLAGS="$CFLAGS $MOZ_OPTIMIZE_FLAGS"
     AC_TRY_COMPILE([#include <stdio.h>],
@@ -7080,7 +7085,7 @@ if test -n "$MOZ_OPTIMIZE"; then
         _results=no)
     AC_MSG_RESULT([$_results])
     if test "$_results" = "no"; then
-        AC_MSG_ERROR([These compiler flags are invalid: $MOZ_OPTIMIZE_FLAGS])
+        AC_MSG_ERROR([These compiler flags for C are invalid: $MOZ_OPTIMIZE_FLAGS])
     fi
     CFLAGS=$_SAVE_CFLAGS
 fi
@@ -7089,6 +7094,7 @@ fi # COMPILE_ENVIRONMENT
 AC_SUBST(MOZ_OPTIMIZE)
 AC_SUBST(MOZ_FRAMEPTR_FLAGS)
 AC_SUBST(MOZ_OPTIMIZE_FLAGS)
+AC_SUBST(MOZ_OPTIMIZE_RUSTFLAGS)
 AC_SUBST(MOZ_OPTIMIZE_LDFLAGS)
 AC_SUBST(MOZ_ALLOW_HEAP_EXECUTE_FLAGS)
 AC_SUBST(MOZ_PGO)