diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -1162,9 +1162,7 @@
   Synonym for ``__is_final``.
 * ``__is_signed`` (C++, Embarcadero):
   Note that this currently returns true for enumeration types if the underlying
-  type is signed, and returns false for floating-point types, in violation of
-  the requirements for ``std::is_signed``. This behavior is likely to change in
-  a future version of Clang.
+  type is signed, and returns true for floating-point types.
 * ``__is_standard_layout`` (C++, GNU, Microsoft, Embarcadero)
 * ``__is_trivial`` (C++, GNU, Microsoft, Embarcadero)
 * ``__is_trivially_assignable`` (C++, GNU, Microsoft)
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -4605,7 +4605,7 @@
       return RD->hasAttr<FinalAttr>();
     return false;
   case UTT_IsSigned:
-    return T->isSignedIntegerType();
+    return T->isFloatingType() || T->isSignedIntegerType();
   case UTT_IsUnsigned:
     return T->isUnsignedIntegerType();
 
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -56,14 +56,14 @@
 struct HasNoInheritedCons : HasCons {};
 struct HasCopyAssign { HasCopyAssign operator =(const HasCopyAssign&); };
 struct HasMoveAssign { HasMoveAssign operator =(const HasMoveAssign&&); };
-struct HasNoThrowMoveAssign { 
+struct HasNoThrowMoveAssign {
   HasNoThrowMoveAssign& operator=(
     const HasNoThrowMoveAssign&&) throw(); };
-struct HasNoExceptNoThrowMoveAssign { 
+struct HasNoExceptNoThrowMoveAssign {
   HasNoExceptNoThrowMoveAssign& operator=(
-    const HasNoExceptNoThrowMoveAssign&&) noexcept; 
+    const HasNoExceptNoThrowMoveAssign&&) noexcept;
 };
-struct HasThrowMoveAssign { 
+struct HasThrowMoveAssign {
   HasThrowMoveAssign& operator=(const HasThrowMoveAssign&&)
 #if __cplusplus <= 201402L
   throw(POD);
@@ -73,7 +73,7 @@
 };
 
 
-struct HasNoExceptFalseMoveAssign { 
+struct HasNoExceptFalseMoveAssign {
   HasNoExceptFalseMoveAssign& operator=(
     const HasNoExceptFalseMoveAssign&&) noexcept(false); };
 struct HasMoveCtor { HasMoveCtor(const HasMoveCtor&&); };
@@ -82,17 +82,17 @@
 struct HasStaticMemberMoveCtor { static HasMoveCtor member; };
 struct HasStaticMemberMoveAssign { static HasMoveAssign member; };
 struct HasMemberThrowMoveAssign { HasThrowMoveAssign member; };
-struct HasMemberNoExceptFalseMoveAssign { 
+struct HasMemberNoExceptFalseMoveAssign {
   HasNoExceptFalseMoveAssign member; };
 struct HasMemberNoThrowMoveAssign { HasNoThrowMoveAssign member; };
-struct HasMemberNoExceptNoThrowMoveAssign { 
+struct HasMemberNoExceptNoThrowMoveAssign {
   HasNoExceptNoThrowMoveAssign member; };
 
-struct HasDefaultTrivialCopyAssign { 
+struct HasDefaultTrivialCopyAssign {
   HasDefaultTrivialCopyAssign &operator=(
-    const HasDefaultTrivialCopyAssign&) = default; 
+    const HasDefaultTrivialCopyAssign&) = default;
 };
-struct TrivialMoveButNotCopy { 
+struct TrivialMoveButNotCopy {
   TrivialMoveButNotCopy &operator=(TrivialMoveButNotCopy&&) = default;
   TrivialMoveButNotCopy &operator=(const TrivialMoveButNotCopy&);
 };
@@ -361,7 +361,7 @@
 struct FinalClass final {
 };
 
-template<typename T> 
+template<typename T>
 struct PotentiallyFinal { };
 
 template<typename T>
@@ -1419,12 +1419,12 @@
   int t04[T(__is_signed(short))];
   int t05[T(__is_signed(signed char))];
   int t06[T(__is_signed(wchar_t))];
+  int t07[T(__is_signed(float))];
+  int t08[T(__is_signed(double))];
+  int t09[T(__is_signed(long double))];
 
-  int t10[F(__is_signed(bool))];
-  int t11[F(__is_signed(cvoid))];
-  int t12[F(__is_signed(float))];
-  int t13[F(__is_signed(double))];
-  int t14[F(__is_signed(long double))];
+  int t13[F(__is_signed(bool))];
+  int t14[F(__is_signed(cvoid))];
   int t15[F(__is_signed(unsigned char))];
   int t16[F(__is_signed(unsigned int))];
   int t17[F(__is_signed(unsigned long long))];
@@ -2005,7 +2005,7 @@
 };
 
 template<typename T>
-struct X0 { 
+struct X0 {
   template<typename U> X0(const X0<U>&);
 };
 
@@ -2766,7 +2766,7 @@
   char b[7];
 };
 
-static_assert(!has_unique_object_representations<NotUniqueBecauseTailPadding>::value, 
+static_assert(!has_unique_object_representations<NotUniqueBecauseTailPadding>::value,
               "non trivial");
 // Can be unique on Itanium, since the is child class' data is 'folded' into the
 // parent's tail padding.