diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index d4c8327..a687937 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1806,7 +1806,6 @@
   Opts.NoBitFieldTypeAlign = Args.hasArg(OPT_fno_bitfield_type_align);
   Opts.SinglePrecisionConstants = Args.hasArg(OPT_cl_single_precision_constant);
   Opts.FastRelaxedMath = Args.hasArg(OPT_cl_fast_relaxed_math);
-  Opts.OptimizeSize = 0;
   Opts.MRTD = Args.hasArg(OPT_mrtd);
   Opts.FakeAddressSpaceMap = Args.hasArg(OPT_ffake_address_space_map);
   Opts.ParseUnknownAnytype = Args.hasArg(OPT_funknown_anytype);
@@ -1823,6 +1822,7 @@
   // FIXME: Eliminate this dependency.
   unsigned Opt = getOptimizationLevel(Args, IK, Diags);
   Opts.Optimize = Opt != 0;
+  Opts.OptimizeSize = Args.hasArg(OPT_Os) || Args.hasArg(OPT_Oz);
 
   // This is the __NO_INLINE__ define, which just depends on things like the
   // optimization level and -fno-inline, not actually whether the backend has