diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h
index 382a19e5d80..27e164c6641 100644
--- a/include/llvm/ADT/APInt.h
+++ b/include/llvm/ADT/APInt.h
@@ -200,19 +200,19 @@ class LLVM_NODISCARD APInt {
   APInt &AssignSlowCase(const APInt &RHS);
 
   /// out-of-line slow case for operator==
-  bool EqualSlowCase(const APInt &RHS) const;
+  bool EqualSlowCase(const APInt &RHS) const LLVM_READONLY;
 
   /// out-of-line slow case for operator==
-  bool EqualSlowCase(uint64_t Val) const;
+  bool EqualSlowCase(uint64_t Val) const LLVM_READONLY;
 
   /// out-of-line slow case for countLeadingZeros
-  unsigned countLeadingZerosSlowCase() const;
+  unsigned countLeadingZerosSlowCase() const LLVM_READONLY;
 
   /// out-of-line slow case for countTrailingOnes
-  unsigned countTrailingOnesSlowCase() const;
+  unsigned countTrailingOnesSlowCase() const LLVM_READONLY;
 
   /// out-of-line slow case for countPopulation
-  unsigned countPopulationSlowCase() const;
+  unsigned countPopulationSlowCase() const LLVM_READONLY;
 
   /// out-of-line slow case for setBits.
   void setBitsSlowCase(unsigned loBit, unsigned hiBit);
@@ -966,7 +966,7 @@ public:
   /// the validity of the less-than relationship.
   ///
   /// \returns true if *this < RHS when both are considered unsigned.
-  bool ult(const APInt &RHS) const;
+  bool ult(const APInt &RHS) const LLVM_READONLY;
 
   /// \brief Unsigned less than comparison
   ///
@@ -984,7 +984,7 @@ public:
   /// validity of the less-than relationship.
   ///
   /// \returns true if *this < RHS when both are considered signed.
-  bool slt(const APInt &RHS) const;
+  bool slt(const APInt &RHS) const LLVM_READONLY;
 
   /// \brief Signed less than comparison
   ///
@@ -1363,7 +1363,7 @@ public:
   ///
   /// \returns 0 if the high order bit is not set, otherwise returns the number
   /// of 1 bits from the most significant to the least
-  unsigned countLeadingOnes() const;
+  unsigned countLeadingOnes() const LLVM_READONLY;
 
   /// Computes the number of leading bits of this APInt that are equal to its
   /// sign bit.
@@ -1379,7 +1379,7 @@ public:
   ///
   /// \returns BitWidth if the value is zero, otherwise returns the number of
   /// zeros from the least significant bit to the first one bit.
-  unsigned countTrailingZeros() const;
+  unsigned countTrailingZeros() const LLVM_READONLY;
 
   /// \brief Count the number of trailing one bits.
   ///