diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2873,6 +2873,7 @@
       AssociativeMath = true;
       ReciprocalMath = true;
       SignedZeros = false;
+      ApproxFunc = true;
       TrappingMath = false;
       FPExceptionBehavior = "";
       break;
@@ -2880,6 +2881,7 @@
       AssociativeMath = false;
       ReciprocalMath = false;
       SignedZeros = true;
+      ApproxFunc = false;
       TrappingMath = true;
       FPExceptionBehavior = "strict";
 
@@ -2899,6 +2901,7 @@
       MathErrno = false;
       AssociativeMath = true;
       ReciprocalMath = true;
+      ApproxFunc = true;
       SignedZeros = false;
       TrappingMath = false;
       RoundingFPMath = false;
@@ -2914,6 +2917,7 @@
       MathErrno = TC.IsMathErrnoDefault();
       AssociativeMath = false;
       ReciprocalMath = false;
+      ApproxFunc = false;
       SignedZeros = true;
       // -fno_fast_math restores default denormal and fpcontract handling
       DenormalFPMath = DefaultDenormalFPMath;
@@ -2932,7 +2936,7 @@
       // If -ffp-model=strict has been specified on command line but
       // subsequent options conflict then emit warning diagnostic.
       if (HonorINFs && HonorNaNs && !AssociativeMath && !ReciprocalMath &&
-          SignedZeros && TrappingMath && RoundingFPMath &&
+          SignedZeros && TrappingMath && RoundingFPMath && !ApproxFunc &&
           DenormalFPMath == llvm::DenormalMode::getIEEE() &&
           DenormalFP32Math == llvm::DenormalMode::getIEEE() &&
           FPContract.equals("off"))
@@ -2965,7 +2969,7 @@
     CmdArgs.push_back("-fmath-errno");
 
   if (!MathErrno && AssociativeMath && ReciprocalMath && !SignedZeros &&
-      !TrappingMath)
+      ApproxFunc && !TrappingMath)
     CmdArgs.push_back("-menable-unsafe-fp-math");
 
   if (!SignedZeros)
@@ -3016,7 +3020,7 @@
   // -ffast-math enables the __FAST_MATH__ preprocessor macro, but check for the
   // individual features enabled by -ffast-math instead of the option itself as
   // that's consistent with gcc's behaviour.
-  if (!HonorINFs && !HonorNaNs && !MathErrno && AssociativeMath &&
+  if (!HonorINFs && !HonorNaNs && !MathErrno && AssociativeMath && ApproxFunc &&
       ReciprocalMath && !SignedZeros && !TrappingMath && !RoundingFPMath) {
     CmdArgs.push_back("-ffast-math");
     if (FPModel.equals("fast")) {
diff --git a/clang/test/Driver/fast-math.c b/clang/test/Driver/fast-math.c
--- a/clang/test/Driver/fast-math.c
+++ b/clang/test/Driver/fast-math.c
@@ -70,6 +70,23 @@
 // CHECK-NO-NANS-NO-FAST-MATH: "-cc1"
 // CHECK-NO-NANS-NO-FAST-MATH-NOT: "-menable-no-nans"
 //
+// RUN: %clang -### -ffast-math -fno-approx-func -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-FAST-MATH-NO-APPROX-FUNC %s
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-cc1"
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-menable-no-infs"
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-menable-no-nans"
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-fno-signed-zeros"
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-mreassociate"
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-freciprocal-math"
+// CHECK-FAST-MATH-NO-APPROX-FUNC:     "-ffp-contract=fast"
+// CHECK-FAST-MATH-NO-APPROX-FUNC-NOT: "-ffast-math"
+// CHECK-FAST-MATH-NO-APPROX-FUNC-NOT: "-fapprox-func"
+//
+// RUN: %clang -### -fno-approx-func -ffast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-APPROX-FUNC-FAST-MATH %s
+// CHECK-NO-APPROX-FUNC-FAST-MATH: "-cc1"
+// CHECK-NO-APPROX-FUNC-FAST-MATH: "-ffast-math"
+//
 // RUN: %clang -### -fapprox-func -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-APPROX-FUNC %s
 // CHECK-APPROX-FUNC: "-cc1"
@@ -130,14 +147,14 @@
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
 //
 // RUN: %clang -### -fno-math-errno -fassociative-math -freciprocal-math \
-// RUN:     -fno-signed-zeros -fno-trapping-math -c %s 2>&1 \
+// RUN:     -fno-signed-zeros -fno-trapping-math -fapprox-func -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-UNSAFE-MATH %s
 // CHECK-UNSAFE-MATH: "-cc1"
 // CHECK-UNSAFE-MATH: "-menable-unsafe-fp-math"
 // CHECK-UNSAFE-MATH: "-mreassociate"
 //
 // RUN: %clang -### -fno-fast-math -fno-math-errno -fassociative-math -freciprocal-math \
-// RUN:     -fno-signed-zeros -fno-trapping-math -c %s 2>&1 \
+// RUN:     -fno-signed-zeros -fno-trapping-math -fapprox-func -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-NO-FAST-MATH-UNSAFE-MATH %s
 // CHECK-NO-FAST-MATH-UNSAFE-MATH: "-cc1"
 // CHECK-NO-FAST-MATH-UNSAFE-MATH: "-menable-unsafe-fp-math"
@@ -178,7 +195,7 @@
 // RUN:     -fno-math-errno -ffp-contract=fast -fno-rounding-math -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-FAST-MATH %s
 // RUN: %clang -### -fno-honor-infinities -fno-honor-nans -fno-math-errno \
-// RUN:     -fassociative-math -freciprocal-math -fno-signed-zeros \
+// RUN:     -fassociative-math -freciprocal-math -fno-signed-zeros -fapprox-func \
 // RUN:     -fno-trapping-math -ffp-contract=fast -fno-rounding-math -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-FAST-MATH %s
 // CHECK-FAST-MATH: "-cc1"
diff --git a/clang/test/Preprocessor/aarch64-target-features.c b/clang/test/Preprocessor/aarch64-target-features.c
--- a/clang/test/Preprocessor/aarch64-target-features.c
+++ b/clang/test/Preprocessor/aarch64-target-features.c
@@ -115,7 +115,7 @@
 // CHECK-CRC32: __ARM_FEATURE_CRC32 1
 
 // RUN: %clang -target aarch64-none-linux-gnu -fno-math-errno -fno-signed-zeros\
-// RUN:        -fno-trapping-math -fassociative-math -freciprocal-math\
+// RUN:        -fno-trapping-math -fassociative-math -freciprocal-math -fapprox-func\
 // RUN:        -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
 // RUN: %clang -target aarch64-none-linux-gnu -ffast-math -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
 // RUN: %clang -target arm64-none-linux-gnu -ffast-math -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
diff --git a/clang/test/Preprocessor/arm-target-features.c b/clang/test/Preprocessor/arm-target-features.c
--- a/clang/test/Preprocessor/arm-target-features.c
+++ b/clang/test/Preprocessor/arm-target-features.c
@@ -267,7 +267,7 @@
 // CHECK-DEFS:#define __ARM_SIZEOF_WCHAR_T 4
 
 // RUN: %clang -target arm-none-linux-gnu -fno-math-errno -fno-signed-zeros\
-// RUN:        -fno-trapping-math -fassociative-math -freciprocal-math\
+// RUN:        -fno-trapping-math -fassociative-math -freciprocal-math -fapprox-func\
 // RUN:        -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=CHECK-FASTMATH %s
 // RUN: %clang -target arm-none-linux-gnu -ffast-math -x c -E -dM %s -o -\
 // RUN:        | FileCheck -match-full-lines --check-prefix=CHECK-FASTMATH %s