diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
@@ -12,6 +12,7 @@
 #include "../misc/NonPrivateMemberVariablesInClassesCheck.h"
 #include "../misc/UnconventionalAssignOperatorCheck.h"
 #include "../modernize/AvoidCArraysCheck.h"
+#include "../modernize/UseDefaultMemberInitCheck.h"
 #include "../modernize/UseOverrideCheck.h"
 #include "../readability/MagicNumbersCheck.h"
 #include "AvoidCapturingLambdaCoroutinesCheck.h"
@@ -110,6 +111,8 @@
     CheckFactories.registerCheck<SpecialMemberFunctionsCheck>(
         "cppcoreguidelines-special-member-functions");
     CheckFactories.registerCheck<SlicingCheck>("cppcoreguidelines-slicing");
+    CheckFactories.registerCheck<modernize::UseDefaultMemberInitCheck>(
+        "cppcoreguidelines-use-default-member-init");
     CheckFactories.registerCheck<misc::UnconventionalAssignOperatorCheck>(
         "cppcoreguidelines-c-copy-assignment-signature");
     CheckFactories.registerCheck<VirtualClassDestructorCheck>(
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
@@ -176,139 +176,98 @@
     const Expr *InitValue;
     std::tie(Field, InitValue) = isAssignmentToMemberOf(Class, S, Ctor);
     if (Field) {
-      if (IsUseDefaultMemberInitEnabled && getLangOpts().CPlusPlus11 &&
-          Ctor->isDefaultConstructor() &&
-          (getLangOpts().CPlusPlus20 || !Field->isBitField()) &&
-          !Field->hasInClassInitializer() &&
-          (!isa<RecordDecl>(Class->getDeclContext()) ||
-           !cast<RecordDecl>(Class->getDeclContext())->isUnion()) &&
-          shouldBeDefaultMemberInitializer(InitValue)) {
-
-        bool InvalidFix = false;
-        SourceLocation FieldEnd =
-            Lexer::getLocForEndOfToken(Field->getSourceRange().getEnd(), 0,
-                                       *Result.SourceManager, getLangOpts());
-        InvalidFix |= FieldEnd.isInvalid() || FieldEnd.isMacroID();
-        SourceLocation SemiColonEnd;
-        if (auto NextToken = Lexer::findNextToken(
-                S->getEndLoc(), *Result.SourceManager, getLangOpts()))
-          SemiColonEnd = NextToken->getEndLoc();
-        else
-          InvalidFix = true;
-        auto Diag =
-            diag(S->getBeginLoc(), "%0 should be initialized in an in-class"
-                                   " default member initializer")
-            << Field;
-        if (InvalidFix)
+      StringRef InsertPrefix = "";
+      bool HasInitAlready = false;
+      SourceLocation InsertPos;
+      SourceRange ReplaceRange;
+      bool AddComma = false;
+      bool InvalidFix = false;
+      unsigned Index = Field->getFieldIndex();
+      const CXXCtorInitializer *LastInListInit = nullptr;
+      for (const CXXCtorInitializer *Init : Ctor->inits()) {
+        if (!Init->isWritten() || Init->isInClassMemberInitializer())
           continue;
-        CharSourceRange StmtRange =
-            CharSourceRange::getCharRange(S->getBeginLoc(), SemiColonEnd);
-
-        SmallString<128> Insertion(
-            {UseAssignment ? " = " : "{",
-             Lexer::getSourceText(
-                 CharSourceRange(InitValue->getSourceRange(), true),
-                 *Result.SourceManager, getLangOpts()),
-             UseAssignment ? "" : "}"});
-
-        Diag << FixItHint::CreateInsertion(FieldEnd, Insertion)
-             << FixItHint::CreateRemoval(StmtRange);
-
-      } else {
-        StringRef InsertPrefix = "";
-        bool HasInitAlready = false;
-        SourceLocation InsertPos;
-        SourceRange ReplaceRange;
-        bool AddComma = false;
-        bool InvalidFix = false;
-        unsigned Index = Field->getFieldIndex();
-        const CXXCtorInitializer *LastInListInit = nullptr;
-        for (const CXXCtorInitializer *Init : Ctor->inits()) {
-          if (!Init->isWritten() || Init->isInClassMemberInitializer())
-            continue;
-          if (Init->getMember() == Field) {
-            HasInitAlready = true;
-            if (isa<ImplicitValueInitExpr>(Init->getInit()))
-              InsertPos = Init->getRParenLoc();
-            else {
-              ReplaceRange = Init->getInit()->getSourceRange();
-            }
-            break;
+        if (Init->getMember() == Field) {
+          HasInitAlready = true;
+          if (isa<ImplicitValueInitExpr>(Init->getInit()))
+            InsertPos = Init->getRParenLoc();
+          else {
+            ReplaceRange = Init->getInit()->getSourceRange();
           }
-          if (Init->isMemberInitializer() &&
-              Index < Init->getMember()->getFieldIndex()) {
-            InsertPos = Init->getSourceLocation();
-            // There are initializers after the one we are inserting, so add a
-            // comma after this insertion in order to not break anything.
-            AddComma = true;
-            break;
-          }
-          LastInListInit = Init;
+          break;
         }
-        if (HasInitAlready) {
-          if (InsertPos.isValid())
-            InvalidFix |= InsertPos.isMacroID();
-          else
-            InvalidFix |= ReplaceRange.getBegin().isMacroID() ||
-                          ReplaceRange.getEnd().isMacroID();
-        } else {
-          if (InsertPos.isInvalid()) {
-            if (LastInListInit) {
-              InsertPos = Lexer::getLocForEndOfToken(
-                  LastInListInit->getRParenLoc(), 0, *Result.SourceManager,
-                  getLangOpts());
-              // Inserting after the last constructor initializer, so we need a
-              // comma.
-              InsertPrefix = ", ";
-            } else {
-              InsertPos = Lexer::getLocForEndOfToken(
-                  Ctor->getTypeSourceInfo()
-                      ->getTypeLoc()
-                      .getAs<clang::FunctionTypeLoc>()
-                      .getLocalRangeEnd(),
-                  0, *Result.SourceManager, getLangOpts());
-
-              // If this is first time in the loop, there are no initializers so
-              // `:` declares member initialization list. If this is a
-              // subsequent pass then we have already inserted a `:` so continue
-              // with a comma.
-              InsertPrefix = FirstToCtorInits ? " : " : ", ";
-            }
-          }
+        if (Init->isMemberInitializer() &&
+            Index < Init->getMember()->getFieldIndex()) {
+          InsertPos = Init->getSourceLocation();
+          // There are initializers after the one we are inserting, so add a
+          // comma after this insertion in order to not break anything.
+          AddComma = true;
+          break;
+        }
+        LastInListInit = Init;
+      }
+      if (HasInitAlready) {
+        if (InsertPos.isValid())
           InvalidFix |= InsertPos.isMacroID();
+        else
+          InvalidFix |= ReplaceRange.getBegin().isMacroID() ||
+                        ReplaceRange.getEnd().isMacroID();
+      } else {
+        if (InsertPos.isInvalid()) {
+          if (LastInListInit) {
+            InsertPos = Lexer::getLocForEndOfToken(
+                LastInListInit->getRParenLoc(), 0, *Result.SourceManager,
+                getLangOpts());
+            // Inserting after the last constructor initializer, so we need a
+            // comma.
+            InsertPrefix = ", ";
+          } else {
+            InsertPos = Lexer::getLocForEndOfToken(
+                Ctor->getTypeSourceInfo()
+                    ->getTypeLoc()
+                    .getAs<clang::FunctionTypeLoc>()
+                    .getLocalRangeEnd(),
+                0, *Result.SourceManager, getLangOpts());
+
+            // If this is first time in the loop, there are no initializers so
+            // `:` declares member initialization list. If this is a
+            // subsequent pass then we have already inserted a `:` so continue
+            // with a comma.
+            InsertPrefix = FirstToCtorInits ? " : " : ", ";
+          }
         }
+        InvalidFix |= InsertPos.isMacroID();
+      }
 
-        SourceLocation SemiColonEnd;
-        if (auto NextToken = Lexer::findNextToken(
-                S->getEndLoc(), *Result.SourceManager, getLangOpts()))
-          SemiColonEnd = NextToken->getEndLoc();
+      SourceLocation SemiColonEnd;
+      if (auto NextToken = Lexer::findNextToken(
+              S->getEndLoc(), *Result.SourceManager, getLangOpts()))
+        SemiColonEnd = NextToken->getEndLoc();
+      else
+        InvalidFix = true;
+
+      auto Diag = diag(S->getBeginLoc(), "%0 should be initialized in a member"
+                                         " initializer of the constructor")
+                  << Field;
+      if (InvalidFix)
+        continue;
+      StringRef NewInit = Lexer::getSourceText(
+          CharSourceRange(InitValue->getSourceRange(), true),
+          *Result.SourceManager, getLangOpts());
+      if (HasInitAlready) {
+        if (InsertPos.isValid())
+          Diag << FixItHint::CreateInsertion(InsertPos, NewInit);
         else
-          InvalidFix = true;
-
-        auto Diag =
-            diag(S->getBeginLoc(), "%0 should be initialized in a member"
-                                   " initializer of the constructor")
-            << Field;
-        if (InvalidFix)
-          continue;
-        StringRef NewInit = Lexer::getSourceText(
-            CharSourceRange(InitValue->getSourceRange(), true),
-            *Result.SourceManager, getLangOpts());
-        if (HasInitAlready) {
-          if (InsertPos.isValid())
-            Diag << FixItHint::CreateInsertion(InsertPos, NewInit);
-          else
-            Diag << FixItHint::CreateReplacement(ReplaceRange, NewInit);
-        } else {
-          SmallString<128> Insertion({InsertPrefix, Field->getName(), "(",
-                                      NewInit, AddComma ? "), " : ")"});
-          Diag << FixItHint::CreateInsertion(InsertPos, Insertion,
-                                             FirstToCtorInits);
-          FirstToCtorInits = areDiagsSelfContained();
-        }
-        Diag << FixItHint::CreateRemoval(
-            CharSourceRange::getCharRange(S->getBeginLoc(), SemiColonEnd));
+          Diag << FixItHint::CreateReplacement(ReplaceRange, NewInit);
+      } else {
+        SmallString<128> Insertion({InsertPrefix, Field->getName(), "(",
+                                    NewInit, AddComma ? "), " : ")"});
+        Diag << FixItHint::CreateInsertion(InsertPos, Insertion,
+                                           FirstToCtorInits);
+        FirstToCtorInits = areDiagsSelfContained();
       }
+      Diag << FixItHint::CreateRemoval(
+          CharSourceRange::getCharRange(S->getBeginLoc(), SemiColonEnd));
     }
   }
 }
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -174,6 +174,11 @@
   <clang-tidy/checks/cert/msc33-c>` to :doc:`bugprone-unsafe-functions
   <clang-tidy/checks/bugprone/unsafe-functions>` was added.
 
+- New alias :doc:`cppcoreguidelines-use-default-member-init
+  <clang-tidy/checks/cppcoreguidelines/use-default-member-init>` to
+  :doc:`modernize-use-default-member-init
+  <clang-tidy/checks/modernize/use-default-member-init>` was added.
+
 Changes in existing checks
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 - Improved :doc:`readability-redundant-string-cstr
@@ -215,6 +220,11 @@
 - Deprecated :doc:`cert-dcl21-cpp
   <clang-tidy/checks/cert/dcl21-cpp>` check.
 
+- Move C.48 enforcement from :doc:`cppcoreguidelines-prefer-member-initializer
+  <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` to
+  :doc:`cppcoreguidelines-use-default-member-init
+  <clang-tidy/checks/cppcoreguidelines/use-default-member-init>`.
+
 - Deprecated check-local options `HeaderFileExtensions`
   in :doc:`google-build-namespaces
   <clang-tidy/checks/google/build-namespaces>` check.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/prefer-member-initializer.rst b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/prefer-member-initializer.rst
--- a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/prefer-member-initializer.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/prefer-member-initializer.rst
@@ -11,18 +11,6 @@
 
 This check implements `C.49 <https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c49-prefer-initialization-to-assignment-in-constructors>`_ from the CppCoreGuidelines.
 
-If the language version is `C++ 11` or above, the constructor is the default
-constructor of the class, the field is not a bitfield (only in case of earlier
-language version than `C++ 20`), furthermore the assigned value is a literal,
-negated literal or ``enum`` constant then the preferred place of the
-initialization is at the class member declaration.
-
-This latter rule is `C.48 <https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c48-prefer-in-class-initializers-to-member-initializers-in-constructors-for-constant-initializers>`_ from CppCoreGuidelines.
-
-Please note, that this check does not enforce this latter rule for
-initializations already implemented as member initializers. For that purpose
-see check `modernize-use-default-member-init <../modernize/use-default-member-init.html>`_.
-
 Example 1
 ---------
 
@@ -40,16 +28,16 @@
     }
   };
 
-Here ``n`` can be initialized using a default member initializer, unlike
+Here ``n`` can be initialized in the member initializer list, unlike
 ``m``, as ``m``'s initialization follows a control statement (``if``):
 
 .. code-block:: c++
 
   class C {
-    int n{1};
+    int n;
     int m;
   public:
-    C() {
+    C(): n(1) {
       if (dice())
         return;
       m = 1;
@@ -82,22 +70,3 @@
       return;
     m = mm;
   }
-
-.. option:: UseAssignment
-
-   If this option is set to `true` (default is `false`), the check will initialize
-   members with an assignment. In this case the fix of the first example looks
-   like this:
-
-.. code-block:: c++
-
-  class C {
-    int n = 1;
-    int m;
-  public:
-    C() {
-      if (dice())
-        return;
-      m = 1;
-    }
-  };
diff --git a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/use-default-member-init.rst b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/use-default-member-init.rst
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/use-default-member-init.rst
@@ -0,0 +1,12 @@
+.. title:: clang-tidy - cppcoreguidelines-use-default-member-init
+.. meta::
+   :http-equiv=refresh: 5;URL=../modernize/use-default-member-init.html
+
+cppcoreguidelines-use-default-member-init
+=========================================
+
+This check implements `C.48 <https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c48-prefer-in-class-initializers-to-member-initializers-in-constructors-for-constant-initializers>`_ from the CppCoreGuidelines.
+
+The cppcoreguidelines-use-default-member-init check is an alias, please see
+`modernize-use-default-member-init <../modernize/use-default-member-init.html>`_
+for more information.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -207,6 +207,7 @@
    `cppcoreguidelines-rvalue-reference-param-not-moved <cppcoreguidelines/rvalue-reference-param-not-moved.html>`_,
    `cppcoreguidelines-slicing <cppcoreguidelines/slicing.html>`_,
    `cppcoreguidelines-special-member-functions <cppcoreguidelines/special-member-functions.html>`_,
+   `cppcoreguidelines-use-default-member-init <cppcoreguidelines/use-default-member-init.html>`_, "Yes"
    `cppcoreguidelines-virtual-class-destructor <cppcoreguidelines/virtual-class-destructor.html>`_, "Yes"
    `darwin-avoid-spinlock <darwin/avoid-spinlock.html>`_,
    `darwin-dispatch-once-nonstatic <darwin/dispatch-once-nonstatic.html>`_, "Yes"
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer-modernize-use-default-member-init-assignment.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer-modernize-use-default-member-init-assignment.cpp
deleted file mode 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer-modernize-use-default-member-init-assignment.cpp
+++ /dev/null
@@ -1,31 +0,0 @@
-// RUN: %check_clang_tidy %s cppcoreguidelines-prefer-member-initializer,modernize-use-default-member-init %t -- \
-// RUN: -config="{CheckOptions: [{key: modernize-use-default-member-init.UseAssignment, value: true}]}"
-
-class Simple1 {
-  int n;
-  // CHECK-FIXES: int n = 0;
-  double x;
-  // CHECK-FIXES: double x = 0.0;
-
-public:
-  Simple1() {
-    n = 0;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'n' should be initialized in an in-class default member initializer [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-    x = 0.0;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'x' should be initialized in an in-class default member initializer [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-  }
-
-  Simple1(int nn, double xx) {
-    // CHECK-FIXES: Simple1(int nn, double xx) : n(nn), x(xx) {
-    n = nn;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'n' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-    x = xx;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'x' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-  }
-
-  ~Simple1() = default;
-};
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer-modernize-use-default-member-init.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer-modernize-use-default-member-init.cpp
deleted file mode 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer-modernize-use-default-member-init.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-// RUN: %check_clang_tidy %s cppcoreguidelines-prefer-member-initializer,modernize-use-default-member-init %t
-
-class Simple1 {
-  int n;
-  // CHECK-FIXES: int n{0};
-  double x;
-  // CHECK-FIXES: double x{0.0};
-
-public:
-  Simple1() {
-    n = 0;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'n' should be initialized in an in-class default member initializer [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-    x = 0.0;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'x' should be initialized in an in-class default member initializer [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-  }
-
-  Simple1(int nn, double xx) {
-    // CHECK-FIXES: Simple1(int nn, double xx) : n(nn), x(xx) {
-    n = nn;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'n' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-    x = xx;
-    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'x' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
-    // CHECK-FIXES: {{^\ *$}}
-  }
-
-  ~Simple1() = default;
-};