diff --git a/include/bx/inline/math.inl b/include/bx/inline/math.inl
index 331490e..97e3b4c 100644
--- a/include/bx/inline/math.inl
+++ b/include/bx/inline/math.inl
@@ -138,6 +138,24 @@ namespace bx
 		return float( (0.0f < _a) - (0.0f > _a) );
 	}
 
+	inline BX_CONSTEXPR_FUNC bool signbit(float _a)
+	{
+#if BX_COMPILER_MSVC
+		return _signbit(_a);
+#else
+		return __builtin_signbit(_a);
+#endif // BX_COMPILER_MSVC
+	}
+
+	inline BX_CONSTEXPR_FUNC float copysign(float _value, float _sign)
+	{
+#if BX_COMPILER_MSVC
+		return _copysign(_value, _sign);
+#else
+		return __builtin_copysign(_value, _sign);
+#endif // BX_COMPILER_MSVC
+	}
+
 	inline BX_CONSTEXPR_FUNC float abs(float _a)
 	{
 		return _a < 0.0f ? -_a : _a;
diff --git a/include/bx/math.h b/include/bx/math.h
index 26d68ef..7441a28 100644
--- a/include/bx/math.h
+++ b/include/bx/math.h
@@ -174,10 +174,27 @@ namespace bx
 	///
 	/// @param[in] _a Value.
 	///
-	/// @returns -1 if `_a` less than zero, 0 if `_a` is equal to 0, or +1 if `_a` is greater than zero.
+	/// @returns -1 if `_a` is less than zero, 0 if `_a` is equal to 0, or +1 if `_a` is greater than zero.
 	///
 	BX_CONSTEXPR_FUNC float sign(float _a);
 
+	/// Returns `true` if the velue `_a` is negative.
+	///
+	/// @param[in] _a Value.
+	///
+	/// @returns `true` if `_a` is less than zero, otherwise returns `false`.
+	///
+	BX_CONSTEXPR_FUNC bool signbit(float _a);
+
+	/// Returns value with the magnitude `_value`, and the sign of `_sign`.
+	///
+	/// @param[in] _value Value.
+	/// @param[in] _sign Sign.
+	///
+	/// @returns Value with the magnitude `_value`, and the sign of `_sign`.
+	///
+	BX_CONSTEXPR_FUNC float copysign(float _value, float _sign);
+
 	/// Returns the absolute of _a.
 	///
 	BX_CONSTEXPR_FUNC float abs(float _a);
diff --git a/tests/math_test.cpp b/tests/math_test.cpp
index b4f63fd..88f63c3 100644
--- a/tests/math_test.cpp
+++ b/tests/math_test.cpp
@@ -303,9 +303,31 @@ TEST_CASE("atan2", "")
 
 TEST_CASE("sign", "")
 {
-	REQUIRE(-1 == bx::sign(-0.1389f) );
-	REQUIRE( 0 == bx::sign( 0.0000f) );
-	REQUIRE( 1 == bx::sign( 0.1389f) );
+	STATIC_REQUIRE(-1 == bx::sign(-0.1389f) );
+	STATIC_REQUIRE( 0 == bx::sign( 0.0000f) );
+	STATIC_REQUIRE( 1 == bx::sign( 0.1389f) );
+
+	REQUIRE(-1 == bx::sign(-bx::kFloatInfinity) );
+	REQUIRE( 1 == bx::sign( bx::kFloatInfinity) );
+}
+
+TEST_CASE("signbit", "")
+{
+	STATIC_REQUIRE( bx::signbit(-0.1389f) );
+	STATIC_REQUIRE(!bx::signbit( 0.0000f) );
+	STATIC_REQUIRE(!bx::signbit( 0.1389f) );
+
+	REQUIRE( bx::signbit(-bx::kFloatInfinity) );
+	REQUIRE(!bx::signbit( bx::kFloatInfinity) );
+}
+
+TEST_CASE("copysign", "")
+{
+	STATIC_REQUIRE( 0.1389f == bx::copysign(-0.1389f, +1389) );
+	STATIC_REQUIRE(-0.0000f == bx::copysign( 0.0000f, -1389) );
+	STATIC_REQUIRE(-0.1389f == bx::copysign( 0.1389f, -1389) );
+
+	REQUIRE(-bx::kFloatInfinity == bx::copysign(bx::kFloatInfinity, -1389) );
 }
 
 TEST_CASE("ToBits", "")