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
@@ -766,9 +766,11 @@
     D.Diag(diag::err_drv_argument_not_allowed_with)
         << ProfileGenerateArg->getSpelling() << ProfileUseArg->getSpelling();
 
-  if (CSPGOGenerateArg && PGOGenerateArg)
+  if (CSPGOGenerateArg && PGOGenerateArg) {
     D.Diag(diag::err_drv_argument_not_allowed_with)
         << CSPGOGenerateArg->getSpelling() << PGOGenerateArg->getSpelling();
+    PGOGenerateArg = nullptr;
+  }
 
   if (ProfileGenerateArg) {
     if (ProfileGenerateArg->getOption().matches(
diff --git a/clang/test/Driver/fcs-profile-generate.c b/clang/test/Driver/fcs-profile-generate.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/fcs-profile-generate.c
@@ -0,0 +1,15 @@
+// RUN: %clang -### -c -fprofile-use=a.profdata -fcs-profile-generate %s 2>&1 | FileCheck %s
+// CHECK:      "-fprofile-instrument=csllvm"
+// CHECK-NOT:  "-fprofile-instrument-path=
+// CHECK-SAME: "-fprofile-instrument-use-path=a.profdata"
+
+// RUN: %clang -### -c -fprofile-use=a.profdata -fcs-profile-generate=dir %s 2>&1 | FileCheck %s --check-prefix=CHECK1
+// CHECK1: "-fprofile-instrument=csllvm"{{.*}} "-fprofile-instrument-path=dir{{/|\\\\}}default_%m.profraw" "-fprofile-instrument-use-path=a.profdata"
+
+/// Degradation case. This usage does not make much sense.
+// RUN: %clang -### -c -fcs-profile-generate %s 2>&1 | FileCheck %s --check-prefix=NOUSE
+// NOUSE:     "-fprofile-instrument=csllvm"
+// NOUSE-NOT: "-fprofile-instrument-path=
+
+// RUN: %clang -### -c -fprofile-generate -fcs-profile-generate %s 2>&1 | FileCheck %s --check-prefix=CONFLICT
+// CONFLICT: error: invalid argument '-fcs-profile-generate' not allowed with '-fprofile-generate'