diff --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h
--- a/llvm/include/llvm/Support/MathExtras.h
+++ b/llvm/include/llvm/Support/MathExtras.h
@@ -91,3 +91,3 @@
 template <typename T, std::size_t SizeOfT> struct TrailingZerosCounter {
-  static unsigned count(T Val, ZeroBehavior) {
+  static constexpr unsigned count(T Val, ZeroBehavior) {
     if (!Val)
@@ -115,3 +115,3 @@
 template <typename T> struct TrailingZerosCounter<T, 4> {
-  static unsigned count(T Val, ZeroBehavior ZB) {
+  static constexpr unsigned count(T Val, ZeroBehavior ZB) {
     if (ZB != ZB_Undefined && Val == 0)
@@ -131,3 +131,3 @@
 template <typename T> struct TrailingZerosCounter<T, 8> {
-  static unsigned count(T Val, ZeroBehavior ZB) {
+  static constexpr unsigned count(T Val, ZeroBehavior ZB) {
     if (ZB != ZB_Undefined && Val == 0)
@@ -156,3 +156,3 @@
 template <typename T>
-unsigned countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
+constexpr unsigned countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
   static_assert(std::numeric_limits<T>::is_integer &&
@@ -165,3 +165,3 @@
 template <typename T, std::size_t SizeOfT> struct LeadingZerosCounter {
-  static unsigned count(T Val, ZeroBehavior) {
+  static constexpr unsigned count(T Val, ZeroBehavior) {
     if (!Val)
@@ -184,3 +184,3 @@
 template <typename T> struct LeadingZerosCounter<T, 4> {
-  static unsigned count(T Val, ZeroBehavior ZB) {
+  static constexpr unsigned count(T Val, ZeroBehavior ZB) {
     if (ZB != ZB_Undefined && Val == 0)
@@ -200,3 +200,3 @@
 template <typename T> struct LeadingZerosCounter<T, 8> {
-  static unsigned count(T Val, ZeroBehavior ZB) {
+  static constexpr unsigned count(T Val, ZeroBehavior ZB) {
     if (ZB != ZB_Undefined && Val == 0)
@@ -225,3 +225,3 @@
 template <typename T>
-unsigned countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
+constexpr unsigned countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
   static_assert(std::numeric_limits<T>::is_integer &&