diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e43a931c1922132340faea26c2cc5a66fbc77a50..299206492a7d93aed58621e04df818efe8fe271e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2018-04-24  Jakub Jelinek  <jakub@redhat.com>
 
+	PR target/85511
+	* config/i386/i386.c (ix86_init_mmx_sse_builtins): Don't define
+	__builtin_ia32_readeflags_u32 and __builtin_ia32_writeeflags_u32
+	if TARGET_64BIT.
+
 	PR target/85503
 	* config/rs6000/rs6000-p8swap.c (const_load_sequence_p): Punt if
 	const_vector is not CONST_VECTOR or SYMBOL_REF for a constant pool
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index fada22bba7021a97725c766092385c89bac55861..a3c3870d4f4df4c2c2b5dff1954e69de474dfae1 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -31934,14 +31934,20 @@ ix86_init_mmx_sse_builtins (void)
 	       IX86_BUILTIN_SBB64);
 
   /* Read/write FLAGS.  */
-  def_builtin (0, "__builtin_ia32_readeflags_u32",
-               UNSIGNED_FTYPE_VOID, IX86_BUILTIN_READ_FLAGS);
-  def_builtin (OPTION_MASK_ISA_64BIT, "__builtin_ia32_readeflags_u64",
-               UINT64_FTYPE_VOID, IX86_BUILTIN_READ_FLAGS);
-  def_builtin (0, "__builtin_ia32_writeeflags_u32",
-               VOID_FTYPE_UNSIGNED, IX86_BUILTIN_WRITE_FLAGS);
-  def_builtin (OPTION_MASK_ISA_64BIT, "__builtin_ia32_writeeflags_u64",
-               VOID_FTYPE_UINT64, IX86_BUILTIN_WRITE_FLAGS);
+  if (TARGET_64BIT)
+    {
+      def_builtin (OPTION_MASK_ISA_64BIT, "__builtin_ia32_readeflags_u64",
+		   UINT64_FTYPE_VOID, IX86_BUILTIN_READ_FLAGS);
+      def_builtin (OPTION_MASK_ISA_64BIT, "__builtin_ia32_writeeflags_u64",
+		   VOID_FTYPE_UINT64, IX86_BUILTIN_WRITE_FLAGS);
+    }
+  else
+    {
+      def_builtin (0, "__builtin_ia32_readeflags_u32",
+		   UNSIGNED_FTYPE_VOID, IX86_BUILTIN_READ_FLAGS);
+      def_builtin (0, "__builtin_ia32_writeeflags_u32",
+		   VOID_FTYPE_UNSIGNED, IX86_BUILTIN_WRITE_FLAGS);
+    }
 
   /* CLFLUSHOPT.  */
   def_builtin (OPTION_MASK_ISA_CLFLUSHOPT, "__builtin_ia32_clflushopt",
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0c1c0be9e91175e051ddb3bd2b48225fa5e37f74..12fd465de84719fc467e32783d06d71f300be9a1 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2018-04-24  Jakub Jelinek  <jakub@redhat.com>
 
+	PR target/85511
+	* gcc.target/i386/pr85511.c: New test.
+
 	PR target/85503
 	* g++.dg/ext/pr85503.C: New test.
 
diff --git a/gcc/testsuite/gcc.target/i386/pr85511.c b/gcc/testsuite/gcc.target/i386/pr85511.c
new file mode 100644
index 0000000000000000000000000000000000000000..a082a5eaf018b5301329baf7b7ed91ccbdc863f4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr85511.c
@@ -0,0 +1,15 @@
+/* PR target/85511 */
+/* { dg-do compile } */
+/* { dg-options "-Wimplicit-function-declaration" } */
+
+unsigned int
+foo (void)
+{
+  return __builtin_ia32_readeflags_u32 ();	/* { dg-warning "implicit declaration of function" "" { target { ! ia32 } } } */
+}
+
+void
+bar (unsigned int x)
+{
+  __builtin_ia32_writeeflags_u32 (x);		/* { dg-warning "implicit declaration of function" "" { target { ! ia32 } } } */
+}