Index: compiler-rt/lib/builtins/CMakeLists.txt
===================================================================
--- compiler-rt/lib/builtins/CMakeLists.txt
+++ compiler-rt/lib/builtins/CMakeLists.txt
@@ -239,6 +239,7 @@
   floatuntixf.c
   mulxc3.c
   powixf2.c
+  i386/fp_mode.c
 )
 
 if (NOT MSVC)
Index: compiler-rt/lib/builtins/i386/fp_mode.c
===================================================================
--- /dev/null
+++ compiler-rt/lib/builtins/i386/fp_mode.c
@@ -0,0 +1,71 @@
+//===----- lib/i386/fp_mode.c - Floaing-point mode utilities -----*- C -*-====//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdint.h>
+
+#include "../fp_mode.h"
+
+#define X87_TONEAREST  0x0000
+#define X87_DOWNWARD   0x0400
+#define X87_UPWARD     0x0800
+#define X87_TOWARDZERO 0x0c00
+#define X87_RMODE_MASK (X87_TONEAREST | X87_UPWARD | X87_DOWNWARD | X87_TOWARDZERO)
+
+#define X87_INEXACT    0x20
+
+typedef struct {
+  unsigned short __control_word;
+  unsigned short __unused1;
+  unsigned short __status_word;
+  unsigned short __unused2;
+  unsigned short __tags;
+  unsigned short __unused3;
+  unsigned int   __eip;
+  unsigned short __cs_selector;
+  unsigned short __opcode;
+  unsigned int   __data_offset;
+  unsigned short __data_selector;
+  unsigned short __unused5;
+#ifdef __X86_64__
+  unsigned int   __mxcsr;
+#endif
+} fenv_t;
+
+FE_ROUND_MODE __fe_getround() {
+  // Assume that the rounding mode state for the fpu agrees with the SSE unit.
+  unsigned short cw;
+  __asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
+
+  switch (cw & X87_RMODE_MASK) {
+    case X87_TONEAREST:
+      return FE_TONEAREST;
+    case X87_DOWNWARD:
+      return FE_DOWNWARD;
+    case X87_UPWARD:
+      return FE_UPWARD;
+    case X87_TOWARDZERO:
+      return FE_TOWARDZERO;
+  }
+  return FE_TONEAREST;
+}
+
+int __fe_raise_inexact() {
+  fenv_t env;
+  __asm__ __volatile__ ("fnstenv %0": "=m" (env));
+  env.__status_word |= X87_INEXACT;
+  __asm__ __volatile__ ("fnclex");
+  __asm__ __volatile__ ("fldenv %0": : "m" (env));
+
+#ifdef __SSE_MATH__
+  uint32_t mxcsr;
+  __asm__ __volatile__ ("stmxcsr %0": "=m" (mxcsr));
+  mxcsr |= X87_INEXACT;
+  __asm__ __volatile__ ("ldmxcsr %0": : "m" (mxcsr));
+#endif
+  return 0;
+}
Index: compiler-rt/test/builtins/Unit/addtf3_test.c
===================================================================
--- compiler-rt/test/builtins/Unit/addtf3_test.c
+++ compiler-rt/test/builtins/Unit/addtf3_test.c
@@ -76,7 +76,8 @@
                      UINT64_C(0x61e58dd6c51eb77c)))
         return 1;
 
-#if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP)
+#if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) || \
+    defined(i386) || defined(__x86_64__)
     // Rounding mode tests on supported architectures
     const long double m = 1234.0L, n = 0.01L;
 
Index: compiler-rt/test/builtins/Unit/subtf3_test.c
===================================================================
--- compiler-rt/test/builtins/Unit/subtf3_test.c
+++ compiler-rt/test/builtins/Unit/subtf3_test.c
@@ -69,7 +69,8 @@
                      UINT64_C(0xa44a7bca780a166c)))
         return 1;
 
-#if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP)
+#if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) || \
+    defined(i386) || defined(__x86_64__)
     // Rounding mode tests on supported architectures
     const long double m = 1234.02L, n = 0.01L;