diff --git a/llvm/include/llvm/ADT/ArrayRef.h b/llvm/include/llvm/ADT/ArrayRef.h
--- a/llvm/include/llvm/ADT/ArrayRef.h
+++ b/llvm/include/llvm/ADT/ArrayRef.h
@@ -605,49 +605,57 @@
   /// @}
 
   /// Construct a MutableArrayRef from a single element.
-  template<typename T>
+  template <typename T>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(T &OneElt) {
     return OneElt;
   }
 
   /// Construct a MutableArrayRef from a pointer and length.
-  template<typename T>
+  template <typename T>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(T *data, size_t length) {
     return MutableArrayRef<T>(data, length);
   }
 
   /// Construct a MutableArrayRef from a SmallVector.
   template <typename T>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(SmallVectorImpl<T> &Vec) {
     return Vec;
   }
 
   /// Construct a MutableArrayRef from a SmallVector.
   template <typename T, unsigned N>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(SmallVector<T, N> &Vec) {
     return Vec;
   }
 
   /// Construct a MutableArrayRef from a std::vector.
-  template<typename T>
+  template <typename T>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(std::vector<T> &Vec) {
     return Vec;
   }
 
   /// Construct a MutableArrayRef from a std::array.
   template <typename T, std::size_t N>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(std::array<T, N> &Arr) {
     return Arr;
   }
 
   /// Construct a MutableArrayRef from a MutableArrayRef (no-op) (const)
   template <typename T>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(const MutableArrayRef<T> &Vec) {
     return Vec;
   }
 
   /// Construct a MutableArrayRef from a C array.
-  template<typename T, size_t N>
+  template <typename T, size_t N>
+  LLVM_DEPRECATED("Use deduction guide instead", "MutableArrayRef")
   MutableArrayRef<T> makeMutableArrayRef(T (&Arr)[N]) {
     return MutableArrayRef<T>(Arr);
   }
diff --git a/llvm/unittests/ADT/ArrayRefTest.cpp b/llvm/unittests/ADT/ArrayRefTest.cpp
--- a/llvm/unittests/ADT/ArrayRefTest.cpp
+++ b/llvm/unittests/ADT/ArrayRefTest.cpp
@@ -258,45 +258,6 @@
 static_assert(std::is_trivially_copyable_v<ArrayRef<int>>,
               "trivially copyable");
 
-TEST(ArrayRefTest, makeMutableArrayRef) {
-  int A = 0;
-  auto AR = makeMutableArrayRef(A);
-  EXPECT_EQ(AR.data(), &A);
-  EXPECT_EQ(AR.size(), (size_t)1);
-
-  AR[0] = 1;
-  EXPECT_EQ(A, 1);
-
-  int B[] = {0, 1, 2, 3};
-  auto BR1 = makeMutableArrayRef(&B[0], 4);
-  auto BR2 = makeMutableArrayRef(B);
-  EXPECT_EQ(BR1.data(), &B[0]);
-  EXPECT_EQ(BR1.size(), (size_t)4);
-  EXPECT_EQ(BR2.data(), &B[0]);
-  EXPECT_EQ(BR2.size(), (size_t)4);
-
-  SmallVector<int> C1;
-  SmallVectorImpl<int> &C2 = C1;
-  C1.resize(5);
-  auto CR1 = makeMutableArrayRef(C1);
-  auto CR2 = makeMutableArrayRef(C2);
-  EXPECT_EQ(CR1.data(), C1.data());
-  EXPECT_EQ(CR1.size(), C1.size());
-  EXPECT_EQ(CR2.data(), C2.data());
-  EXPECT_EQ(CR2.size(), C2.size());
-
-  std::vector<int> D;
-  D.resize(5);
-  auto DR = makeMutableArrayRef(D);
-  EXPECT_EQ(DR.data(), D.data());
-  EXPECT_EQ(DR.size(), D.size());
-
-  std::array<int, 5> E;
-  auto ER = makeMutableArrayRef(E);
-  EXPECT_EQ(ER.data(), E.data());
-  EXPECT_EQ(ER.size(), E.size());
-}
-
 TEST(ArrayRefTest, MutableArrayRefDeductionGuides) {
   // Single element
   {