diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 0f82f01e57a71..ede95e3b2ca9b 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -170,6 +170,7 @@
 #![feature(internal_impls_macro)]
 #![feature(ip)]
 #![feature(is_ascii_octdigit)]
+#![feature(is_val_statically_known)]
 #![feature(isqrt)]
 #![feature(link_cfg)]
 #![feature(offset_of_enum)]
diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
index d40e02352a1d0..d8ef36f21ac63 100644
--- a/library/core/src/num/int_macros.rs
+++ b/library/core/src/num/int_macros.rs
@@ -1495,18 +1495,17 @@ macro_rules! int_impl {
             let mut base = self;
             let mut acc: Self = 1;
 
-            while exp > 1 {
+            loop {
                 if (exp & 1) == 1 {
                     acc = try_opt!(acc.checked_mul(base));
+                    // since exp!=0, finally the exp must be 1.
+                    if exp == 1 {
+                        return Some(acc);
+                    }
                 }
                 exp /= 2;
                 base = try_opt!(base.checked_mul(base));
             }
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.checked_mul(base)
         }
 
         /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
@@ -1546,18 +1545,17 @@ macro_rules! int_impl {
             let mut base = self;
             let mut acc: Self = 1;
 
-            while exp > 1 {
+            loop {
                 if (exp & 1) == 1 {
                     acc = acc.strict_mul(base);
+                    // since exp!=0, finally the exp must be 1.
+                    if exp == 1 {
+                        return acc;
+                    }
                 }
                 exp /= 2;
                 base = base.strict_mul(base);
             }
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.strict_mul(base)
         }
 
         /// Returns the square root of the number, rounded down.
@@ -2174,6 +2172,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known)]
         pub const fn wrapping_pow(self, mut exp: u32) -> Self {
             if exp == 0 {
                 return 1;
@@ -2181,19 +2180,36 @@ macro_rules! int_impl {
             let mut base = self;
             let mut acc: Self = 1;
 
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc.wrapping_mul(base);
+            if intrinsics::is_val_statically_known(exp) {
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc.wrapping_mul(base);
+                    }
+                    exp /= 2;
+                    base = base.wrapping_mul(base);
                 }
-                exp /= 2;
-                base = base.wrapping_mul(base);
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.wrapping_mul(base)
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary.
+                acc.wrapping_mul(base)
+            } else {
+                // This is faster than the above when the exponent is not known
+                // at compile time. We can't use the same code for the constant
+                // exponent case because LLVM is currently unable to unroll
+                // this loop.
+                loop {
+                    if (exp & 1) == 1 {
+                        acc = acc.wrapping_mul(base);
+                        // since exp!=0, finally the exp must be 1.
+                        if exp == 1 {
+                            return acc;
+                        }
+                    }
+                    exp /= 2;
+                    base = base.wrapping_mul(base);
+                }
+            }
         }
 
         /// Calculates `self` + `rhs`
@@ -2687,9 +2703,14 @@ macro_rules! int_impl {
             // Scratch space for storing results of overflowing_mul.
             let mut r;
 
-            while exp > 1 {
+            loop {
                 if (exp & 1) == 1 {
                     r = acc.overflowing_mul(base);
+                    // since exp!=0, finally the exp must be 1.
+                    if exp == 1 {
+                        r.1 |= overflown;
+                        return r;
+                    }
                     acc = r.0;
                     overflown |= r.1;
                 }
@@ -2698,14 +2719,6 @@ macro_rules! int_impl {
                 base = r.0;
                 overflown |= r.1;
             }
-
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            r = acc.overflowing_mul(base);
-            r.1 |= overflown;
-            r
         }
 
         /// Raises self to the power of `exp`, using exponentiation by squaring.
@@ -2725,6 +2738,7 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[inline]
         #[rustc_inherit_overflow_checks]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known)]
         pub const fn pow(self, mut exp: u32) -> Self {
             if exp == 0 {
                 return 1;
@@ -2732,19 +2746,37 @@ macro_rules! int_impl {
             let mut base = self;
             let mut acc = 1;
 
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc * base;
+            if intrinsics::is_val_statically_known(exp) {
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc * base;
+                    }
+                    exp /= 2;
+                    base = base * base;
                 }
-                exp /= 2;
-                base = base * base;
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc * base
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc * base
+            } else {
+                // This is faster than the above when the exponent is not known
+                // at compile time. We can't use the same code for the constant
+                // exponent case because LLVM is currently unable to unroll
+                // this loop.
+                loop {
+                    if (exp & 1) == 1 {
+                        acc = acc * base;
+                        // since exp!=0, finally the exp must be 1.
+                        if exp == 1 {
+                            return acc;
+                        }
+                    }
+                    exp /= 2;
+                    base = base * base;
+                }
+            }
         }
 
         /// Returns the square root of the number, rounded down.
diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index ad72c29758bd7..5b3ef78d39a3d 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs
@@ -1534,20 +1534,17 @@ macro_rules! uint_impl {
             let mut base = self;
             let mut acc: Self = 1;
 
-            while exp > 1 {
+            loop {
                 if (exp & 1) == 1 {
                     acc = try_opt!(acc.checked_mul(base));
+                    // since exp!=0, finally the exp must be 1.
+                    if exp == 1 {
+                        return Some(acc);
+                    }
                 }
                 exp /= 2;
                 base = try_opt!(base.checked_mul(base));
             }
-
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-
-            acc.checked_mul(base)
         }
 
         /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
@@ -1587,18 +1584,17 @@ macro_rules! uint_impl {
             let mut base = self;
             let mut acc: Self = 1;
 
-            while exp > 1 {
+            loop {
                 if (exp & 1) == 1 {
                     acc = acc.strict_mul(base);
+                    // since exp!=0, finally the exp must be 1.
+                    if exp == 1 {
+                        return acc;
+                    }
                 }
                 exp /= 2;
                 base = base.strict_mul(base);
             }
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.strict_mul(base)
         }
 
         /// Saturating integer addition. Computes `self + rhs`, saturating at
@@ -2052,6 +2048,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known)]
         pub const fn wrapping_pow(self, mut exp: u32) -> Self {
             if exp == 0 {
                 return 1;
@@ -2059,19 +2056,36 @@ macro_rules! uint_impl {
             let mut base = self;
             let mut acc: Self = 1;
 
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc.wrapping_mul(base);
+            if intrinsics::is_val_statically_known(exp) {
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc.wrapping_mul(base);
+                    }
+                    exp /= 2;
+                    base = base.wrapping_mul(base);
                 }
-                exp /= 2;
-                base = base.wrapping_mul(base);
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.wrapping_mul(base)
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary.
+                acc.wrapping_mul(base)
+            } else {
+                // This is faster than the above when the exponent is not known
+                // at compile time. We can't use the same code for the constant
+                // exponent case because LLVM is currently unable to unroll
+                // this loop.
+                loop {
+                    if (exp & 1) == 1 {
+                        acc = acc.wrapping_mul(base);
+                        // since exp!=0, finally the exp must be 1.
+                        if exp == 1 {
+                            return acc;
+                        }
+                    }
+                    exp /= 2;
+                    base = base.wrapping_mul(base);
+                }
+            }
         }
 
         /// Calculates `self` + `rhs`
@@ -2516,9 +2530,14 @@ macro_rules! uint_impl {
             // Scratch space for storing results of overflowing_mul.
             let mut r;
 
-            while exp > 1 {
+            loop {
                 if (exp & 1) == 1 {
                     r = acc.overflowing_mul(base);
+                    // since exp!=0, finally the exp must be 1.
+                    if exp == 1 {
+                        r.1 |= overflown;
+                        return r;
+                    }
                     acc = r.0;
                     overflown |= r.1;
                 }
@@ -2527,15 +2546,6 @@ macro_rules! uint_impl {
                 base = r.0;
                 overflown |= r.1;
             }
-
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            r = acc.overflowing_mul(base);
-            r.1 |= overflown;
-
-            r
         }
 
         /// Raises self to the power of `exp`, using exponentiation by squaring.
@@ -2553,6 +2563,7 @@ macro_rules! uint_impl {
                       without modifying the original"]
         #[inline]
         #[rustc_inherit_overflow_checks]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known)]
         pub const fn pow(self, mut exp: u32) -> Self {
             if exp == 0 {
                 return 1;
@@ -2560,19 +2571,37 @@ macro_rules! uint_impl {
             let mut base = self;
             let mut acc = 1;
 
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc * base;
+            if intrinsics::is_val_statically_known(exp) {
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc * base;
+                    }
+                    exp /= 2;
+                    base = base * base;
                 }
-                exp /= 2;
-                base = base * base;
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc * base
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc * base
+            } else {
+                // This is faster than the above when the exponent is not known
+                // at compile time. We can't use the same code for the constant
+                // exponent case because LLVM is currently unable to unroll
+                // this loop.
+                loop {
+                    if (exp & 1) == 1 {
+                        acc = acc * base;
+                        // since exp!=0, finally the exp must be 1.
+                        if exp == 1 {
+                            return acc;
+                        }
+                    }
+                    exp /= 2;
+                    base = base * base;
+                }
+            }
         }
 
         /// Returns the square root of the number, rounded down.