diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 26a9792e6a6087..3d8240f8357b40 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -445,7 +445,7 @@ def warn_drv_deprecated_arg_no_relaxed_template_template_args : Warning<
   "argument '-fno-relaxed-template-template-args' is deprecated">,
   InGroup<DeprecatedNoRelaxedTemplateTemplateArgs>;
 def warn_drv_deprecated_arg_ofast : Warning<
-  "argument '-Ofast' is deprecated; use '-O3 -ffast math' for the same behavior,"
+  "argument '-Ofast' is deprecated; use '-O3 -ffast-math' for the same behavior,"
   " or '-O3' to enable only conforming optimizations">,
   InGroup<DeprecatedOFast>;
 def warn_drv_deprecated_custom : Warning<
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 12b20fe04675bf..fecfa2f3c7dba9 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -932,7 +932,7 @@ def O_flag : Flag<["-"], "O">, Visibility<[ClangOption, CC1Option, FC1Option]>,
   Alias<O>, AliasArgs<["1"]>;
 def Ofast : Joined<["-"], "Ofast">, Group<O_Group>,
   Visibility<[ClangOption, CC1Option, FlangOption]>,
-  HelpText<"Deprecated; use '-O3 -ffast math' for the same behavior,"
+  HelpText<"Deprecated; use '-O3 -ffast-math' for the same behavior,"
   " or '-O3' to enable only conforming optimizations">;
 def P : Flag<["-"], "P">,
   Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
diff --git a/clang/test/Driver/Ofast.c b/clang/test/Driver/Ofast.c
index 4c63caf9865d50..91de296a4c3ff7 100644
--- a/clang/test/Driver/Ofast.c
+++ b/clang/test/Driver/Ofast.c
@@ -10,7 +10,7 @@
 // RUN: %clang -Ofast -fno-strict-aliasing -### %s 2>&1 | FileCheck -check-prefix=CHECK-OFAST-NO-STRICT-ALIASING %s
 // RUN: %clang -Ofast -fno-vectorize -### %s 2>&1 | FileCheck -check-prefix=CHECK-OFAST-NO-VECTORIZE %s
 
-// CHECK-OFAST: use '-O3 -ffast math' for the same behavior, or '-O3' to enable only conforming optimizations
+// CHECK-OFAST: use '-O3 -ffast-math' for the same behavior, or '-O3' to enable only conforming optimizations
 // CHECK-OFAST: -cc1
 // CHECK-OFAST-NOT: -relaxed-aliasing
 // CHECK-OFAST: -ffast-math
@@ -25,21 +25,21 @@
 // CHECK-OFAST-O2-NOT: -Ofast
 // CHECK-OFAST-O2: -vectorize-loops
 
-// CHECK-OFAST-NO-FAST-MATH: use '-O3 -ffast math' for the same behavior, or '-O3' to enable only conforming optimizations
+// CHECK-OFAST-NO-FAST-MATH: use '-O3 -ffast-math' for the same behavior, or '-O3' to enable only conforming optimizations
 // CHECK-OFAST-NO-FAST-MATH: -cc1
 // CHECK-OFAST-NO-FAST-MATH-NOT: -relaxed-aliasing
 // CHECK-OFAST-NO-FAST-MATH-NOT: -ffast-math
 // CHECK-OFAST-NO-FAST-MATH: -Ofast
 // CHECK-OFAST-NO-FAST-MATH: -vectorize-loops
 
-// CHECK-OFAST-NO-STRICT-ALIASING: use '-O3 -ffast math' for the same behavior, or '-O3' to enable only conforming optimizations
+// CHECK-OFAST-NO-STRICT-ALIASING: use '-O3 -ffast-math' for the same behavior, or '-O3' to enable only conforming optimizations
 // CHECK-OFAST-NO-STRICT-ALIASING: -cc1
 // CHECK-OFAST-NO-STRICT-ALIASING: -relaxed-aliasing
 // CHECK-OFAST-NO-STRICT-ALIASING: -ffast-math
 // CHECK-OFAST-NO-STRICT-ALIASING: -Ofast
 // CHECK-OFAST-NO-STRICT-ALIASING: -vectorize-loops
 
-// CHECK-OFAST-NO-VECTORIZE: use '-O3 -ffast math' for the same behavior, or '-O3' to enable only conforming optimizations
+// CHECK-OFAST-NO-VECTORIZE: use '-O3 -ffast-math' for the same behavior, or '-O3' to enable only conforming optimizations
 // CHECK-OFAST-NO-VECTORIZE: -cc1
 // CHECK-OFAST-NO-VECTORIZE-NOT: -relaxed-aliasing
 // CHECK-OFAST-NO-VECTORIZE: -ffast-math