diff --git a/js/src/jsnum.cpp b/js/src/jsnum.cpp
index 065139fa2b01..767f221eab5d 100644
--- a/js/src/jsnum.cpp
+++ b/js/src/jsnum.cpp
@@ -65,6 +65,7 @@ using mozilla::Abs;
 using mozilla::AsciiAlphanumericToNumber;
 using mozilla::IsAsciiAlphanumeric;
 using mozilla::IsAsciiDigit;
+using mozilla::MaxNumberValue;
 using mozilla::Maybe;
 using mozilla::MinNumberValue;
 using mozilla::NegativeInfinity;
@@ -1447,7 +1448,7 @@ static const JSPropertySpec number_static_properties[] = {
                  JSPROP_READONLY | JSPROP_PERMANENT),
     JS_DOUBLE_PS("NEGATIVE_INFINITY", mozilla::NegativeInfinity<double>(),
                  JSPROP_READONLY | JSPROP_PERMANENT),
-    JS_DOUBLE_PS("MAX_VALUE", 1.7976931348623157E+308,
+    JS_DOUBLE_PS("MAX_VALUE", MaxNumberValue<double>(),
                  JSPROP_READONLY | JSPROP_PERMANENT),
     JS_DOUBLE_PS("MIN_VALUE", MinNumberValue<double>(),
                  JSPROP_READONLY | JSPROP_PERMANENT),
diff --git a/mfbt/FloatingPoint.h b/mfbt/FloatingPoint.h
index 73dd8e9c3c5f..ad9362152ae9 100644
--- a/mfbt/FloatingPoint.h
+++ b/mfbt/FloatingPoint.h
@@ -216,24 +216,14 @@ static MOZ_ALWAYS_INLINE int_fast16_t ExponentComponent(T aValue) {
 
 /** Returns +Infinity. */
 template <typename T>
-static MOZ_ALWAYS_INLINE T PositiveInfinity() {
-  /*
-   * Positive infinity has all exponent bits set, sign bit set to 0, and no
-   * significand.
-   */
-  typedef FloatingPoint<T> Traits;
-  return BitwiseCast<T>(Traits::kExponentBits);
+static constexpr MOZ_ALWAYS_INLINE T PositiveInfinity() {
+  return std::numeric_limits<T>::infinity();
 }
 
 /** Returns -Infinity. */
 template <typename T>
-static MOZ_ALWAYS_INLINE T NegativeInfinity() {
-  /*
-   * Negative infinity has all exponent bits set, sign bit set to 1, and no
-   * significand.
-   */
-  typedef FloatingPoint<T> Traits;
-  return BitwiseCast<T>(Traits::kSignBit | Traits::kExponentBits);
+static constexpr MOZ_ALWAYS_INLINE T NegativeInfinity() {
+  return -std::numeric_limits<T>::infinity();
 }
 
 /**
@@ -306,10 +296,14 @@ SpecificNaN(int signbit, typename FloatingPoint<T>::Bits significand) {
 
 /** Computes the smallest non-zero positive float/double value. */
 template <typename T>
-static MOZ_ALWAYS_INLINE T MinNumberValue() {
-  typedef FloatingPoint<T> Traits;
-  typedef typename Traits::Bits Bits;
-  return BitwiseCast<T>(Bits(1));
+static constexpr MOZ_ALWAYS_INLINE T MinNumberValue() {
+  return std::numeric_limits<T>::denorm_min();
+}
+
+/** Computes the largest positive float/double value. */
+template <typename T>
+static constexpr MOZ_ALWAYS_INLINE T MaxNumberValue() {
+  return std::numeric_limits<T>::max();
 }
 
 namespace detail {