diff --git a/src/Makefile.in b/src/Makefile.in
index 552dd2e50a..dfd322553b 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -377,11 +377,14 @@ pdmp :=
 # Flags that might be in WARN_CFLAGS but are not valid for Objective C.
 NON_OBJC_CFLAGS = -Wignored-attributes -Wignored-qualifiers -Wopenmp-simd

+# Cajole GCC into inlining key ops even if it wouldn't normally.
+KEY_OPS_CFLAGS = $(if $(filter -Og,$(CFLAGS)),-DDEFINE_KEY_OPS_AS_MACROS)
+
 # -Demacs makes some files produce the correct version for use in Emacs.
 # MYCPPFLAGS is for by-hand Emacs-specific overrides, e.g.,
 # "make MYCPPFLAGS='-DDBUS_DEBUG'".
-EMACS_CFLAGS=-Demacs $(MYCPPFLAGS) -I. -I$(srcdir) \
-  -I$(lib) -I$(top_srcdir)/lib \
+EMACS_CFLAGS = -Demacs $(KEY_OPS_CFLAGS) $(MYCPPFLAGS) \
+  -I. -I$(srcdir) -I$(lib) -I$(top_srcdir)/lib \
   $(C_SWITCH_MACHINE) $(C_SWITCH_SYSTEM) $(C_SWITCH_X_SITE) \
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(DBUS_CFLAGS) \
diff --git a/src/lisp.h b/src/lisp.h
index f223814d8f..7fc3af992e 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -411,15 +411,19 @@ #define lisp_h_XHASH(a) XUFIXNUM_RAW (a)
 # define lisp_h_XTYPE(a) ((enum Lisp_Type) (XLI (a) & ~VALMASK))
 #endif

-/* When compiling via gcc -O0, define the key operations as macros, as
-   Emacs is too slow otherwise.  To disable this optimization, compile
-   with -DINLINING=false.  */
-#if (defined __NO_INLINE__ \
-     && ! defined __OPTIMIZE__ && ! defined __OPTIMIZE_SIZE__ \
-     && ! (defined INLINING && ! INLINING))
-# define DEFINE_KEY_OPS_AS_MACROS true
-#else
-# define DEFINE_KEY_OPS_AS_MACROS false
+/* When DEFINE_KEY_OPS_AS_MACROS, define key operations as macros to
+   cajole the compiler into inlining them; otherwise define them as
+   inline functions as this is cleaner and can be more efficient.
+   The default is true if the compiler is GCC-like and if function
+   inlining is disabled because the compiler is not optimizing or is
+   optimizing for size.  Otherwise the default is false.  */
+#ifndef DEFINE_KEY_OPS_AS_MACROS
+# if (defined __NO_INLINE__ \
+      && ! defined __OPTIMIZE__ && ! defined __OPTIMIZE_SIZE__)
+#  define DEFINE_KEY_OPS_AS_MACROS true
+# else
+#  define DEFINE_KEY_OPS_AS_MACROS false
+# endif
 #endif

 #if DEFINE_KEY_OPS_AS_MACROS