diff --git a/gcc/common/config/i386/i386-common.c b/gcc/common/config/i386/i386-common.c
index 6a7b5c8312f..e156cc34584 100644
--- a/gcc/common/config/i386/i386-common.c
+++ b/gcc/common/config/i386/i386-common.c
@@ -150,6 +150,7 @@ along with GCC; see the file COPYING3.  If not see
 #define OPTION_MASK_ISA_F16C_SET \
   (OPTION_MASK_ISA_F16C | OPTION_MASK_ISA_AVX_SET)
 #define OPTION_MASK_ISA2_MWAITX_SET OPTION_MASK_ISA2_MWAITX
+#define OPTION_MASK_ISA2_MWAIT_SET OPTION_MASK_ISA2_MWAIT
 #define OPTION_MASK_ISA2_CLZERO_SET OPTION_MASK_ISA2_CLZERO
 #define OPTION_MASK_ISA_PKU_SET OPTION_MASK_ISA_PKU
 #define OPTION_MASK_ISA2_RDPID_SET OPTION_MASK_ISA2_RDPID
@@ -245,6 +246,7 @@ along with GCC; see the file COPYING3.  If not see
 #define OPTION_MASK_ISA_XSAVES_UNSET OPTION_MASK_ISA_XSAVES
 #define OPTION_MASK_ISA_CLWB_UNSET OPTION_MASK_ISA_CLWB
 #define OPTION_MASK_ISA2_MWAITX_UNSET OPTION_MASK_ISA2_MWAITX
+#define OPTION_MASK_ISA2_MWAIT_UNSET OPTION_MASK_ISA2_MWAIT
 #define OPTION_MASK_ISA2_CLZERO_UNSET OPTION_MASK_ISA2_CLZERO
 #define OPTION_MASK_ISA_PKU_UNSET OPTION_MASK_ISA_PKU
 #define OPTION_MASK_ISA2_RDPID_UNSET OPTION_MASK_ISA2_RDPID
@@ -1546,6 +1548,19 @@ ix86_handle_option (struct gcc_options *opts,
 	}
       return true;
 
+    case OPT_mmwait:
+      if (value)
+	{
+	  opts->x_ix86_isa_flags2 |= OPTION_MASK_ISA2_MWAIT_SET;
+	  opts->x_ix86_isa_flags2_explicit |= OPTION_MASK_ISA2_MWAIT_SET;
+	}
+      else
+	{
+	  opts->x_ix86_isa_flags2 &= ~OPTION_MASK_ISA2_MWAIT_UNSET;
+	  opts->x_ix86_isa_flags2_explicit |= OPTION_MASK_ISA2_MWAIT_UNSET;
+	}
+      return true;
+
     case OPT_mclzero:
       if (value)
 	{
diff --git a/gcc/config.gcc b/gcc/config.gcc
index 357b0bed067..a020e0808c9 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -414,7 +414,8 @@ i[34567]86-*-*)
 		       avx512vp2intersectintrin.h avx512vp2intersectvlintrin.h
 		       tsxldtrkintrin.h amxtileintrin.h amxint8intrin.h
 		       amxbf16intrin.h x86gprintrin.h uintrintrin.h
-		       hresetintrin.h keylockerintrin.h avxvnniintrin.h"
+		       hresetintrin.h keylockerintrin.h avxvnniintrin.h
+		       mwaitintrin.h"
 	;;
 x86_64-*-*)
 	cpu_type=i386
@@ -451,7 +452,8 @@ x86_64-*-*)
 		       avx512vp2intersectintrin.h avx512vp2intersectvlintrin.h
 		       tsxldtrkintrin.h amxtileintrin.h amxint8intrin.h
 		       amxbf16intrin.h x86gprintrin.h uintrintrin.h
-		       hresetintrin.h keylockerintrin.h avxvnniintrin.h"
+		       hresetintrin.h keylockerintrin.h avxvnniintrin.h
+		       mwaitintrin.h"
 	;;
 ia64-*-*)
 	extra_headers=ia64intrin.h
diff --git a/gcc/config/i386/i386-builtins.c b/gcc/config/i386/i386-builtins.c
index 4fcdf4b89ee..128bd39816c 100644
--- a/gcc/config/i386/i386-builtins.c
+++ b/gcc/config/i386/i386-builtins.c
@@ -628,9 +628,9 @@ ix86_init_mmx_sse_builtins (void)
 			    VOID_FTYPE_VOID, IX86_BUILTIN_MFENCE);
 
   /* SSE3.  */
-  def_builtin (OPTION_MASK_ISA_SSE3, 0, "__builtin_ia32_monitor",
+  def_builtin (0, OPTION_MASK_ISA2_MWAIT, "__builtin_ia32_monitor",
 	       VOID_FTYPE_PCVOID_UNSIGNED_UNSIGNED, IX86_BUILTIN_MONITOR);
-  def_builtin (OPTION_MASK_ISA_SSE3, 0, "__builtin_ia32_mwait",
+  def_builtin (0, OPTION_MASK_ISA2_MWAIT, "__builtin_ia32_mwait",
 	       VOID_FTYPE_UNSIGNED_UNSIGNED, IX86_BUILTIN_MWAIT);
 
   /* AES */
diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c
index 18d2c0b9f99..7ecd0cf8b8c 100644
--- a/gcc/config/i386/i386-options.c
+++ b/gcc/config/i386/i386-options.c
@@ -207,6 +207,7 @@ static struct ix86_target_opts isa2_opts[] =
   { "-mmovbe",		OPTION_MASK_ISA2_MOVBE },
   { "-mclzero",		OPTION_MASK_ISA2_CLZERO },
   { "-mmwaitx",		OPTION_MASK_ISA2_MWAITX },
+  { "-mmwait",		OPTION_MASK_ISA2_MWAIT },
   { "-mmovdir64b",	OPTION_MASK_ISA2_MOVDIR64B },
   { "-mwaitpkg",	OPTION_MASK_ISA2_WAITPKG },
   { "-mcldemote",	OPTION_MASK_ISA2_CLDEMOTE },
@@ -1015,6 +1016,7 @@ ix86_valid_target_attribute_inner_p (tree fndecl, tree args, char *p_strings[],
     IX86_ATTR_ISA ("fsgsbase",	OPT_mfsgsbase),
     IX86_ATTR_ISA ("rdrnd",	OPT_mrdrnd),
     IX86_ATTR_ISA ("mwaitx",	OPT_mmwaitx),
+    IX86_ATTR_ISA ("mwait",	OPT_mmwait),
     IX86_ATTR_ISA ("clzero",	OPT_mclzero),
     IX86_ATTR_ISA ("pku",	OPT_mpku),
     IX86_ATTR_ISA ("lwp",	OPT_mlwp),
@@ -2612,6 +2614,11 @@ ix86_option_override_internal (bool main_args_p,
       || TARGET_PREFETCHWT1_P (opts->x_ix86_isa_flags))
     ix86_prefetch_sse = true;
 
+  /* Enable mwait/monitor instructions for -msse3.  */
+  if (TARGET_SSE3_P (opts->x_ix86_isa_flags))
+    opts->x_ix86_isa_flags2
+      |= OPTION_MASK_ISA2_MWAIT & ~opts->x_ix86_isa_flags2_explicit;
+
   /* Enable popcnt instruction for -msse4.2 or -mabm.  */
   if (TARGET_SSE4_2_P (opts->x_ix86_isa_flags)
       || TARGET_ABM_P (opts->x_ix86_isa_flags))
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 5583ec6881a..73e118900f7 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -181,6 +181,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define TARGET_CLWB_P(x)	TARGET_ISA_CLWB_P(x)
 #define TARGET_MWAITX	TARGET_ISA2_MWAITX
 #define TARGET_MWAITX_P(x)	TARGET_ISA2_MWAITX_P(x)
+#define TARGET_MWAIT	TARGET_ISA2_MWAIT
+#define TARGET_MWAIT_P(x)	TARGET_ISA2_MWAIT_P(x)
 #define TARGET_PKU	TARGET_ISA_PKU
 #define TARGET_PKU_P(x)	TARGET_ISA_PKU_P(x)
 #define TARGET_SHSTK	TARGET_ISA_SHSTK
diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
index c781fdc8278..7b8547bb1c3 100644
--- a/gcc/config/i386/i386.opt
+++ b/gcc/config/i386/i386.opt
@@ -1162,3 +1162,7 @@ AVXVNNI built-in functions and code generation.
 mneeded
 Target Var(ix86_needed) Save
 Emit GNU_PROPERTY_X86_ISA_1_NEEDED GNU property.
+
+mmwait
+Target Mask(ISA2_MWAIT) Var(ix86_isa_flags2) Save
+Support MWAIT and MONITOR built-in functions and code generation.
diff --git a/gcc/config/i386/mwaitintrin.h b/gcc/config/i386/mwaitintrin.h
new file mode 100644
index 00000000000..1ecbc4abb69
--- /dev/null
+++ b/gcc/config/i386/mwaitintrin.h
@@ -0,0 +1,52 @@
+/* Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GCC is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _MWAITINTRIN_H_INCLUDED
+#define _MWAITINTRIN_H_INCLUDED
+
+#ifndef __MWAIT__
+#pragma GCC push_options
+#pragma GCC target("mwait")
+#define __DISABLE_MWAIT__
+#endif /* __MWAIT__ */
+
+extern __inline void
+__attribute__((__gnu_inline__, __always_inline__, __artificial__))
+_mm_monitor (void const * __P, unsigned int __E, unsigned int __H)
+{
+  __builtin_ia32_monitor (__P, __E, __H);
+}
+
+extern __inline void
+__attribute__((__gnu_inline__, __always_inline__, __artificial__))
+_mm_mwait (unsigned int __E, unsigned int __H)
+{
+  __builtin_ia32_mwait (__E, __H);
+}
+
+#ifdef __DISABLE_MWAIT__
+#undef __DISABLE_MWAIT__
+#pragma GCC pop_options
+#endif /* __DISABLE_MWAIT__ */
+
+#endif /* _MWAITINTRIN_H_INCLUDED */
diff --git a/gcc/config/i386/pmmintrin.h b/gcc/config/i386/pmmintrin.h
index fa9c5bb8b9f..f8102d2be23 100644
--- a/gcc/config/i386/pmmintrin.h
+++ b/gcc/config/i386/pmmintrin.h
@@ -29,6 +29,7 @@
 
 /* We need definitions from the SSE2 and SSE header files*/
 #include <emmintrin.h>
+#include <mwaitintrin.h>
 
 #ifndef __SSE3__
 #pragma GCC push_options
@@ -112,18 +113,6 @@ _mm_lddqu_si128 (__m128i const *__P)
   return (__m128i) __builtin_ia32_lddqu ((char const *)__P);
 }
 
-extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
-_mm_monitor (void const * __P, unsigned int __E, unsigned int __H)
-{
-  __builtin_ia32_monitor (__P, __E, __H);
-}
-
-extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
-_mm_mwait (unsigned int __E, unsigned int __H)
-{
-  __builtin_ia32_mwait (__E, __H);
-}
-
 #ifdef __DISABLE_SSE3__
 #undef __DISABLE_SSE3__
 #pragma GCC pop_options
diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 3f81abc7804..43afe3dabed 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -16593,7 +16593,7 @@ (define_insn "sse3_mwait"
   [(unspec_volatile [(match_operand:SI 0 "register_operand" "c")
 		     (match_operand:SI 1 "register_operand" "a")]
 		    UNSPECV_MWAIT)]
-  "TARGET_SSE3"
+  "TARGET_MWAIT"
 ;; 64bit version is "mwait %rax,%rcx". But only lower 32bits are used.
 ;; Since 32bit register operands are implicitly zero extended to 64bit,
 ;; we only need to set up 32bit registers.
@@ -16605,7 +16605,7 @@ (define_insn "@sse3_monitor_<mode>"
 		     (match_operand:SI 1 "register_operand" "c")
 		     (match_operand:SI 2 "register_operand" "d")]
 		    UNSPECV_MONITOR)]
-  "TARGET_SSE3"
+  "TARGET_MWAIT"
 ;; 64bit version is "monitor %rax,%rcx,%rdx". But only lower 32bits in
 ;; RCX and RDX are used.  Since 32bit register operands are implicitly
 ;; zero extended to 64bit, we only need to set up 32bit registers.
diff --git a/gcc/config/i386/x86gprintrin.h b/gcc/config/i386/x86gprintrin.h
index ceda501252c..7793032ba90 100644
--- a/gcc/config/i386/x86gprintrin.h
+++ b/gcc/config/i386/x86gprintrin.h
@@ -56,6 +56,8 @@
 
 #include <movdirintrin.h>
 
+#include <mwaitintrin.h>
+
 #include <mwaitxintrin.h>
 
 #include <pconfigintrin.h>
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 1bc66cce2b8..1acfaf1d345 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -6665,6 +6665,11 @@ Enable/disable the generation of the MOVDIR64B instructions.
 @cindex @code{target("movdiri")} function attribute, x86
 Enable/disable the generation of the MOVDIRI instructions.
 
+@item mwait
+@itemx no-mwait
+@cindex @code{target("mwait")} function attribute, x86
+Enable/disable the generation of the MWAIT and MONITOR instructions.
+
 @item mwaitx
 @itemx no-mwaitx
 @cindex @code{target("mwaitx")} function attribute, x86
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7f13ffb79e1..3e1f0bc8fad 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1371,7 +1371,7 @@ See RS/6000 and PowerPC Options.
 -mno-wide-multiply  -mrtd  -malign-double @gol
 -mpreferred-stack-boundary=@var{num} @gol
 -mincoming-stack-boundary=@var{num} @gol
--mcld  -mcx16  -msahf  -mmovbe  -mcrc32 @gol
+-mcld  -mcx16  -msahf  -mmovbe  -mcrc32 -mmwait @gol
 -mrecip  -mrecip=@var{opt} @gol
 -mvzeroupper  -mprefer-avx128  -mprefer-vector-width=@var{opt} @gol
 -mmmx  -msse  -msse2  -msse3  -mssse3  -msse4.1  -msse4.2  -msse4  -mavx @gol
@@ -31159,6 +31159,12 @@ This option enables built-in functions @code{__builtin_ia32_crc32qi},
 @code{__builtin_ia32_crc32hi}, @code{__builtin_ia32_crc32si} and
 @code{__builtin_ia32_crc32di} to generate the @code{crc32} machine instruction.
 
+@item -mmwait
+@opindex mmwait
+This option enables built-in functions @code{__builtin_ia32_monitor},
+and @code{__builtin_ia32_mwait} to generate the @code{monitor} and
+@code{mwait} machine instructions.
+
 @item -mrecip
 @opindex mrecip
 This option enables use of @code{RCPSS} and @code{RSQRTSS} instructions
diff --git a/gcc/testsuite/gcc.target/i386/monitor-2.c b/gcc/testsuite/gcc.target/i386/monitor-2.c
new file mode 100644
index 00000000000..96eeec070f0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/monitor-2.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mmwait -mgeneral-regs-only" } */
+
+/* Verify that they work in both 32bit and 64bit.  */
+
+#include <x86gprintrin.h>
+
+void
+foo (char *p, int x, int y, int z)
+{
+   _mm_monitor (p, y, x);
+   _mm_mwait (z, y);
+}
+
+void
+bar (char *p, long x, long y, long z)
+{
+   _mm_monitor (p, y, x);
+   _mm_mwait (z, y);
+}
+
+void
+foo1 (char *p)
+{
+   _mm_monitor (p, 0, 0);
+   _mm_mwait (0, 0);
+}
