diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index 6cd5d618a4aca..57a81e03bc484 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -717,8 +717,15 @@ bool TargetInfo::validateOutputConstraint(ConstraintInfo &Info) const {
   if (*Name != '=' && *Name != '+')
     return false;
 
-  if (*Name == '+')
+  if (*Name == '+') {
     Info.setIsReadWrite();
+    // To align with GCC asm: "=f" is not allowed, the
+    // operand constraints must select a class with a single reg.
+    auto Flag = Name + 1;
+    if (Flag && *Flag == 'f') {
+      return false;
+    }
+  }
 
   Name++;
   while (*Name) {
diff --git a/clang/test/Sema/asm.c b/clang/test/Sema/asm.c
index 630a5e85dd913..a490e9fb5e932 100644
--- a/clang/test/Sema/asm.c
+++ b/clang/test/Sema/asm.c
@@ -359,3 +359,17 @@ void test19(long long x)
   // FIXME: This case should be supported by codegen, but it fails now.
   asm ("" : "=rm" (x): "0" (e)); // expected-error {{unsupported inline asm: input with type 'st_size128' (aka 'struct _st_size128') matching output with type 'long long'}}
 }
+
+void test20()
+{
+  double f00 = 0.0; 
+  double f01 = 0.0; 
+  double f10 = 0.0; 
+  double f11 = 0.0;
+  int mem;
+  asm volatile ("" : "+f" (f00), "+f" (f01), "+f" (f10), "+f" (f11), "+m" (mem) :: "memory"); // expected-error {{invalid output constraint '+f' in asm}}
+  asm volatile ("" : "+r" (f00), "+f" (f01), "+f" (f10), "+f" (f11), "+m" (mem) :: "memory"); // expected-error {{invalid output constraint '+f' in asm}}
+  asm volatile ("" : "+r" (f00), "+r" (f01), "+f" (f10), "+f" (f11), "+m" (mem) :: "memory"); // expected-error {{invalid output constraint '+f' in asm}}
+  asm volatile ("" : "+r" (f00), "+r" (f01), "+r" (f10), "+f" (f11), "+m" (mem) :: "memory"); // expected-error {{invalid output constraint '+f' in asm}}
+  asm volatile ("" : "+r" (f00), "+r" (f01), "+r" (f10), "+r" (f11), "+m" (mem) :: "memory"); // no-error
+}
\ No newline at end of file