diff --git a/lld/MachO/ObjC.cpp b/lld/MachO/ObjC.cpp
index 9d1612beae872e..635ded554497ba 100644
--- a/lld/MachO/ObjC.cpp
+++ b/lld/MachO/ObjC.cpp
@@ -379,12 +379,21 @@ class ObjcCategoryMerger {
     InfoWriteSection catPtrListInfo;
   };
 
-  // Information about a pointer list in the original categories (method lists,
-  // protocol lists, etc)
+  // Information about a pointer list in the original categories or class(method
+  // lists, protocol lists, etc)
   struct PointerListInfo {
+    PointerListInfo() = default;
+    PointerListInfo(const PointerListInfo &) = default;
     PointerListInfo(const char *_categoryPrefix, uint32_t _pointersPerStruct)
         : categoryPrefix(_categoryPrefix),
           pointersPerStruct(_pointersPerStruct) {}
+
+    inline bool operator==(const PointerListInfo &cmp) {
+      return pointersPerStruct == cmp.pointersPerStruct &&
+             structSize == cmp.structSize && structCount == cmp.structCount &&
+             allPtrs == cmp.allPtrs;
+    }
+
     const char *categoryPrefix;
 
     uint32_t pointersPerStruct = 0;
@@ -395,9 +404,9 @@ class ObjcCategoryMerger {
     std::vector<Symbol *> allPtrs;
   };
 
-  // Full information about all the categories that extend a class. This will
-  // include all the additional methods, protocols, and properties that are
-  // contained in all the categories that extend a particular class.
+  // Full information describing an ObjC class . This will include all the
+  // additional methods, protocols, and properties that are contained in the
+  // class and all the categories that extend a particular class.
   struct ClassExtensionInfo {
     ClassExtensionInfo(CategoryLayout &_catLayout) : catLayout(_catLayout){};
 
@@ -449,6 +458,9 @@ class ObjcCategoryMerger {
   void parseProtocolListInfo(const ConcatInputSection *isec, uint32_t secOffset,
                              PointerListInfo &ptrList);
 
+  PointerListInfo parseProtocolListInfo(const ConcatInputSection *isec,
+                                        uint32_t secOffset);
+
   void parsePointerListInfo(const ConcatInputSection *isec, uint32_t secOffset,
                             PointerListInfo &ptrList);
 
@@ -456,9 +468,9 @@ class ObjcCategoryMerger {
                               const ClassExtensionInfo &extInfo,
                               const PointerListInfo &ptrList);
 
-  void emitAndLinkProtocolList(Defined *parentSym, uint32_t linkAtOffset,
-                               const ClassExtensionInfo &extInfo,
-                               const PointerListInfo &ptrList);
+  Defined *emitAndLinkProtocolList(Defined *parentSym, uint32_t linkAtOffset,
+                                   const ClassExtensionInfo &extInfo,
+                                   const PointerListInfo &ptrList);
 
   Defined *emitCategory(const ClassExtensionInfo &extInfo);
   Defined *emitCatListEntrySec(const std::string &forCategoryName,
@@ -474,6 +486,10 @@ class ObjcCategoryMerger {
                                    uint32_t offset);
   Defined *tryGetDefinedAtIsecOffset(const ConcatInputSection *isec,
                                      uint32_t offset);
+  Defined *getClassRo(const Defined *classSym, bool getMetaRo);
+  void mergeCategoriesIntoBaseClass(const Defined *baseClass,
+                                    std::vector<InfoInputCategory> &categories);
+  void eraseSymbolAtIsecOffset(ConcatInputSection *isec, uint32_t offset);
   void tryEraseDefinedAtIsecOffset(const ConcatInputSection *isec,
                                    uint32_t offset);
 
@@ -552,6 +568,29 @@ ObjcCategoryMerger::tryGetDefinedAtIsecOffset(const ConcatInputSection *isec,
   return dyn_cast_or_null<Defined>(sym);
 }
 
+// Get the class's ro_data symbol. If getMetaRo is true, then we will return
+// the meta-class's ro_data symbol. Otherwise, we will return the class
+// (instance) ro_data symbol.
+Defined *ObjcCategoryMerger::getClassRo(const Defined *classSym,
+                                        bool getMetaRo) {
+  ConcatInputSection *isec = dyn_cast<ConcatInputSection>(classSym->isec());
+  if (!isec)
+    return nullptr;
+
+  if (!getMetaRo)
+    return tryGetDefinedAtIsecOffset(isec, classLayout.roDataOffset +
+                                               classSym->value);
+
+  Defined *metaClass = tryGetDefinedAtIsecOffset(
+      isec, classLayout.metaClassOffset + classSym->value);
+  if (!metaClass)
+    return nullptr;
+
+  return tryGetDefinedAtIsecOffset(
+      dyn_cast<ConcatInputSection>(metaClass->isec()),
+      classLayout.roDataOffset);
+}
+
 // Given an ConcatInputSection or CStringInputSection and an offset, if there is
 // a symbol(Defined) at that offset, then erase the symbol (mark it not live)
 void ObjcCategoryMerger::tryEraseDefinedAtIsecOffset(
@@ -663,6 +702,15 @@ void ObjcCategoryMerger::parseProtocolListInfo(const ConcatInputSection *isec,
          "Protocol list end offset does not match expected size");
 }
 
+// Parse a protocol list and return the PointerListInfo for it
+ObjcCategoryMerger::PointerListInfo
+ObjcCategoryMerger::parseProtocolListInfo(const ConcatInputSection *isec,
+                                          uint32_t secOffset) {
+  PointerListInfo ptrList;
+  parseProtocolListInfo(isec, secOffset, ptrList);
+  return ptrList;
+}
+
 // Parse a pointer list that might be linked to ConcatInputSection at a given
 // offset. This can be used for instance methods, class methods, instance props
 // and class props since they have the same format.
@@ -769,11 +817,11 @@ void ObjcCategoryMerger::parseCatInfoToExtInfo(const InfoInputCategory &catInfo,
 
 // Generate a protocol list (including header) and link it into the parent at
 // the specified offset.
-void ObjcCategoryMerger::emitAndLinkProtocolList(
+Defined *ObjcCategoryMerger::emitAndLinkProtocolList(
     Defined *parentSym, uint32_t linkAtOffset,
     const ClassExtensionInfo &extInfo, const PointerListInfo &ptrList) {
   if (ptrList.allPtrs.empty())
-    return;
+    return nullptr;
 
   assert(ptrList.allPtrs.size() == ptrList.structCount);
 
@@ -820,6 +868,8 @@ void ObjcCategoryMerger::emitAndLinkProtocolList(
                           infoCategoryWriter.catPtrListInfo.relocTemplate);
     offset += target->wordSize;
   }
+
+  return ptrListSym;
 }
 
 // Generate a pointer list (including header) and link it into the parent at the
@@ -1265,10 +1315,15 @@ void ObjcCategoryMerger::removeRefsToErasedIsecs() {
 void ObjcCategoryMerger::doMerge() {
   collectAndValidateCategoriesData();
 
-  for (auto &entry : categoryMap)
-    if (entry.second.size() > 1)
+  for (auto &[baseClass, catInfos] : categoryMap) {
+    if (auto *baseClassDef = dyn_cast<Defined>(baseClass)) {
+      // Merge all categories into the base class
+      mergeCategoriesIntoBaseClass(baseClassDef, catInfos);
+    } else if (catInfos.size() > 1) {
       // Merge all categories into a new, single category
-      mergeCategoriesIntoSingleCategory(entry.second);
+      mergeCategoriesIntoSingleCategory(catInfos);
+    }
+  }
 
   // Erase all categories that were merged
   eraseMergedCategories();
@@ -1302,3 +1357,101 @@ void objc::mergeCategories() {
 }
 
 void objc::doCleanup() { ObjcCategoryMerger::doCleanup(); }
+
+void ObjcCategoryMerger::mergeCategoriesIntoBaseClass(
+    const Defined *baseClass, std::vector<InfoInputCategory> &categories) {
+  assert(categories.size() >= 1 && "Expected at least one category to merge");
+
+  // Collect all the info from the categories
+  ClassExtensionInfo extInfo(catLayout);
+  for (auto &catInfo : categories) {
+    parseCatInfoToExtInfo(catInfo, extInfo);
+  }
+
+  // Get metadata for the base class
+  Defined *metaRo = getClassRo(baseClass, /*getMetaRo=*/true);
+  ConcatInputSection *metaIsec = dyn_cast<ConcatInputSection>(metaRo->isec());
+  Defined *classRo = getClassRo(baseClass, /*getMetaRo=*/false);
+  ConcatInputSection *classIsec = dyn_cast<ConcatInputSection>(classRo->isec());
+
+  // Now collect the info from the base class from the various lists in the
+  // class metadata
+
+  // Protocol lists are a special case - the same protocol list is in classRo
+  // and metaRo, so we only need to parse it once
+  parseProtocolListInfo(classIsec, roClassLayout.baseProtocolsOffset,
+                        extInfo.protocols);
+
+  // Check that the classRo and metaRo protocol lists are identical
+  assert(
+      parseProtocolListInfo(classIsec, roClassLayout.baseProtocolsOffset) ==
+          parseProtocolListInfo(metaIsec, roClassLayout.baseProtocolsOffset) &&
+      "Category merger expects classRo and metaRo to have the same protocol "
+      "list");
+
+  parsePointerListInfo(metaIsec, roClassLayout.baseMethodsOffset,
+                       extInfo.classMethods);
+  parsePointerListInfo(classIsec, roClassLayout.baseMethodsOffset,
+                       extInfo.instanceMethods);
+
+  parsePointerListInfo(metaIsec, roClassLayout.basePropertiesOffset,
+                       extInfo.classProps);
+  parsePointerListInfo(classIsec, roClassLayout.basePropertiesOffset,
+                       extInfo.instanceProps);
+
+  // Erase the old lists - these will be generated and replaced
+  eraseSymbolAtIsecOffset(metaIsec, roClassLayout.baseMethodsOffset);
+  eraseSymbolAtIsecOffset(metaIsec, roClassLayout.baseProtocolsOffset);
+  eraseSymbolAtIsecOffset(metaIsec, roClassLayout.basePropertiesOffset);
+  eraseSymbolAtIsecOffset(classIsec, roClassLayout.baseMethodsOffset);
+  eraseSymbolAtIsecOffset(classIsec, roClassLayout.baseProtocolsOffset);
+  eraseSymbolAtIsecOffset(classIsec, roClassLayout.basePropertiesOffset);
+
+  // Emit the newly merged lists - first into the meta RO then into the class RO
+  // First we emit and link the protocol list into the meta RO. Then we link it
+  // in the classRo as well (they're supposed to be identical)
+  if (Defined *protoListSym =
+          emitAndLinkProtocolList(metaRo, roClassLayout.baseProtocolsOffset,
+                                  extInfo, extInfo.protocols)) {
+    createSymbolReference(classRo, protoListSym,
+                          roClassLayout.baseProtocolsOffset,
+                          infoCategoryWriter.catBodyInfo.relocTemplate);
+  }
+
+  emitAndLinkPointerList(metaRo, roClassLayout.baseMethodsOffset, extInfo,
+                         extInfo.classMethods);
+  emitAndLinkPointerList(classRo, roClassLayout.baseMethodsOffset, extInfo,
+                         extInfo.instanceMethods);
+
+  emitAndLinkPointerList(metaRo, roClassLayout.basePropertiesOffset, extInfo,
+                         extInfo.classProps);
+
+  emitAndLinkPointerList(classRo, roClassLayout.basePropertiesOffset, extInfo,
+                         extInfo.instanceProps);
+
+  // Mark all the categories as merged - this will be used to erase them later
+  for (auto &catInfo : categories)
+    catInfo.wasMerged = true;
+}
+
+// Erase the symbol at a given offset in an InputSection
+void ObjcCategoryMerger::eraseSymbolAtIsecOffset(ConcatInputSection *isec,
+                                                 uint32_t offset) {
+  Defined *sym = tryGetDefinedAtIsecOffset(isec, offset);
+  if (!sym)
+    return;
+
+  // Remove the symbol from isec->symbols
+  assert(isa<Defined>(sym) && "Can only erase a Defined");
+  llvm::erase(isec->symbols, sym);
+
+  // Remove the relocs that refer to this symbol
+  auto removeAtOff = [offset](Reloc const &r) { return r.offset == offset; };
+  llvm::erase_if(isec->relocs, removeAtOff);
+
+  // Now, if the symbol fully occupies a ConcatInputSection, we can also erase
+  // the whole ConcatInputSection
+  if (ConcatInputSection *cisec = dyn_cast<ConcatInputSection>(sym->isec()))
+    if (cisec->data.size() == sym->size)
+      eraseISec(cisec);
+}
diff --git a/lld/test/MachO/objc-category-merging-complete-test.s b/lld/test/MachO/objc-category-merging-complete-test.s
index 74400177b550dc..cf3e19e2f9c8b4 100644
--- a/lld/test/MachO/objc-category-merging-complete-test.s
+++ b/lld/test/MachO/objc-category-merging-complete-test.s
@@ -1,6 +1,7 @@
 # REQUIRES: aarch64
 # RUN: rm -rf %t; split-file %s %t && cd %t
 
+############ Test merging multiple categories into a single category ############
 ## Create a dylib to link against(a64_file1.dylib) and merge categories in the main binary (file2_merge_a64.exe)
 # RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o a64_file1.o a64_file1.s
 # RUN: %lld -arch arm64 a64_file1.o -o a64_file1.dylib -dylib
@@ -12,6 +13,10 @@
 # RUN: llvm-objdump --objc-meta-data --macho a64_file2_no_merge.exe | FileCheck %s --check-prefixes=NO_MERGE_CATS
 # RUN: llvm-objdump --objc-meta-data --macho a64_file2_merge.exe | FileCheck %s --check-prefixes=MERGE_CATS
 
+############ Test merging multiple categories into the base class ############
+# RUN: %lld -arch arm64 -o a64_file2_merge_into_class.exe -objc_category_merging a64_file1.o a64_file2.o
+# RUN: llvm-objdump --objc-meta-data --macho a64_file2_merge_into_class.exe | FileCheck %s --check-prefixes=MERGE_CATS_CLS
+
 
 MERGE_CATS:     __OBJC_$_CATEGORY_MyBaseClass(Category02|Category03)
 MERGE_CATS-NEXT:              name {{.*}} Category02|Category03
@@ -101,6 +106,211 @@ NO_MERGE_CATS-NEXT: 24
 NO_MERGE_CATS-NEXT: 2
 
 
+MERGE_CATS_CLS:        _OBJC_CLASS_$_MyBaseClass
+MERGE_CATS_CLS-NEXT:            isa {{.*}} _OBJC_METACLASS_$_MyBaseClass
+MERGE_CATS_CLS-NEXT:     superclass 0x0
+MERGE_CATS_CLS-NEXT:          cache {{.*}} __objc_empty_cache
+MERGE_CATS_CLS-NEXT:         vtable 0x0
+MERGE_CATS_CLS-NEXT:           data {{.*}} (struct class_ro_t *)
+MERGE_CATS_CLS-NEXT:                     flags 0x2 RO_ROOT
+MERGE_CATS_CLS-NEXT:             instanceStart 0
+MERGE_CATS_CLS-NEXT:              instanceSize 4
+MERGE_CATS_CLS-NEXT:                  reserved 0x0
+MERGE_CATS_CLS-NEXT:                ivarLayout 0x0
+MERGE_CATS_CLS-NEXT:                      name {{.*}} MyBaseClass
+MERGE_CATS_CLS-NEXT:               baseMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:            entsize 24
+MERGE_CATS_CLS-NEXT:              count 8
+MERGE_CATS_CLS-NEXT:               name {{.*}} class02InstanceMethod
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass(Category02) class02InstanceMethod]
+MERGE_CATS_CLS-NEXT:               name {{.*}} myProtocol02Method
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass(Category02) myProtocol02Method]
+MERGE_CATS_CLS-NEXT:               name {{.*}} class03InstanceMethod
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass(Category03) class03InstanceMethod]
+MERGE_CATS_CLS-NEXT:               name {{.*}} myProtocol03Method
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass(Category03) myProtocol03Method]
+MERGE_CATS_CLS-NEXT:               name {{.*}} baseInstanceMethod
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass baseInstanceMethod]
+MERGE_CATS_CLS-NEXT:               name {{.*}} myProtocol01Method
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass myProtocol01Method]
+MERGE_CATS_CLS-NEXT:               name {{.*}} MyProtocol01Prop
+MERGE_CATS_CLS-NEXT:              types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass MyProtocol01Prop]
+MERGE_CATS_CLS-NEXT:               name {{.*}} setMyProtocol01Prop:
+MERGE_CATS_CLS-NEXT:              types {{.*}} v20@0:8i16
+MERGE_CATS_CLS-NEXT:                imp -[MyBaseClass setMyProtocol01Prop:]
+MERGE_CATS_CLS-NEXT:             baseProtocols {{.*}}
+MERGE_CATS_CLS-NEXT:                       count 3
+MERGE_CATS_CLS-NEXT:               list[0] {{.*}} (struct protocol_t *)
+MERGE_CATS_CLS-NEXT:                   isa 0x0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol02
+MERGE_CATS_CLS-NEXT:             protocols 0x0
+MERGE_CATS_CLS-NEXT:           instanceMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:                entsize 24
+MERGE_CATS_CLS-NEXT:                  count 2
+MERGE_CATS_CLS-NEXT:                   name {{.*}} myProtocol02Method
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} MyProtocol02Prop
+MERGE_CATS_CLS-NEXT:                  types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:              classMethods 0x0 (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:       optionalInstanceMethods 0x0
+MERGE_CATS_CLS-NEXT:          optionalClassMethods 0x0
+MERGE_CATS_CLS-NEXT:            instanceProperties {{.*}}
+MERGE_CATS_CLS-NEXT:               list[1] {{.*}} (struct protocol_t *)
+MERGE_CATS_CLS-NEXT:                   isa 0x0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol03
+MERGE_CATS_CLS-NEXT:             protocols 0x0
+MERGE_CATS_CLS-NEXT:           instanceMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:                entsize 24
+MERGE_CATS_CLS-NEXT:                  count 2
+MERGE_CATS_CLS-NEXT:                   name {{.*}} myProtocol03Method
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} MyProtocol03Prop
+MERGE_CATS_CLS-NEXT:                  types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:              classMethods 0x0 (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:       optionalInstanceMethods 0x0
+MERGE_CATS_CLS-NEXT:          optionalClassMethods 0x0
+MERGE_CATS_CLS-NEXT:            instanceProperties {{.*}}
+MERGE_CATS_CLS-NEXT:               list[2] {{.*}} (struct protocol_t *)
+MERGE_CATS_CLS-NEXT:                   isa 0x0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol01
+MERGE_CATS_CLS-NEXT:             protocols 0x0
+MERGE_CATS_CLS-NEXT:           instanceMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:                entsize 24
+MERGE_CATS_CLS-NEXT:                  count 3
+MERGE_CATS_CLS-NEXT:                   name {{.*}} myProtocol01Method
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} MyProtocol01Prop
+MERGE_CATS_CLS-NEXT:                  types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} setMyProtocol01Prop:
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v20@0:8i16
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:              classMethods 0x0 (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:       optionalInstanceMethods 0x0
+MERGE_CATS_CLS-NEXT:          optionalClassMethods 0x0
+MERGE_CATS_CLS-NEXT:            instanceProperties {{.*}}
+MERGE_CATS_CLS-NEXT:                     ivars {{.*}}
+MERGE_CATS_CLS-NEXT:                     entsize 32
+MERGE_CATS_CLS-NEXT:                       count 1
+MERGE_CATS_CLS-NEXT:                offset {{.*}} 0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol01Prop
+MERGE_CATS_CLS-NEXT:                  type {{.*}} i
+MERGE_CATS_CLS-NEXT:             alignment 2
+MERGE_CATS_CLS-NEXT:                  size 4
+MERGE_CATS_CLS-NEXT:            weakIvarLayout 0x0
+MERGE_CATS_CLS-NEXT:            baseProperties {{.*}}
+MERGE_CATS_CLS-NEXT:                     entsize 16
+MERGE_CATS_CLS-NEXT:                       count 3
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol02Prop
+MERGE_CATS_CLS-NEXT:             attributes {{.*}} Ti,R,D
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol03Prop
+MERGE_CATS_CLS-NEXT:             attributes {{.*}} Ti,R,D
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol01Prop
+MERGE_CATS_CLS-NEXT:             attributes {{.*}} Ti,N,VMyProtocol01Prop
+MERGE_CATS_CLS-NEXT: Meta Class
+MERGE_CATS_CLS-NEXT:            isa {{.*}} _OBJC_METACLASS_$_MyBaseClass
+MERGE_CATS_CLS-NEXT:     superclass {{.*}} _OBJC_CLASS_$_MyBaseClass
+MERGE_CATS_CLS-NEXT:          cache {{.*}} __objc_empty_cache
+MERGE_CATS_CLS-NEXT:         vtable 0x0
+MERGE_CATS_CLS-NEXT:           data {{.*}} (struct class_ro_t *)
+MERGE_CATS_CLS-NEXT:                     flags 0x3 RO_META RO_ROOT
+MERGE_CATS_CLS-NEXT:             instanceStart 40
+MERGE_CATS_CLS-NEXT:              instanceSize 40
+MERGE_CATS_CLS-NEXT:                  reserved 0x0
+MERGE_CATS_CLS-NEXT:                ivarLayout 0x0
+MERGE_CATS_CLS-NEXT:                      name {{.*}} MyBaseClass
+MERGE_CATS_CLS-NEXT:               baseMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:            entsize 24
+MERGE_CATS_CLS-NEXT:              count 5
+MERGE_CATS_CLS-NEXT:               name {{.*}} class02ClassMethod
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp +[MyBaseClass(Category02) class02ClassMethod]
+MERGE_CATS_CLS-NEXT:               name {{.*}} MyProtocol02Prop
+MERGE_CATS_CLS-NEXT:              types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                imp +[MyBaseClass(Category02) MyProtocol02Prop]
+MERGE_CATS_CLS-NEXT:               name {{.*}} class03ClassMethod
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp +[MyBaseClass(Category03) class03ClassMethod]
+MERGE_CATS_CLS-NEXT:               name {{.*}} MyProtocol03Prop
+MERGE_CATS_CLS-NEXT:              types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                imp +[MyBaseClass(Category03) MyProtocol03Prop]
+MERGE_CATS_CLS-NEXT:               name {{.*}} baseClassMethod
+MERGE_CATS_CLS-NEXT:              types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                imp +[MyBaseClass baseClassMethod]
+MERGE_CATS_CLS-NEXT:             baseProtocols {{.*}}
+MERGE_CATS_CLS-NEXT:                       count 3
+MERGE_CATS_CLS-NEXT:               list[0] {{.*}} (struct protocol_t *)
+MERGE_CATS_CLS-NEXT:                   isa 0x0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol02
+MERGE_CATS_CLS-NEXT:             protocols 0x0
+MERGE_CATS_CLS-NEXT:           instanceMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:                entsize 24
+MERGE_CATS_CLS-NEXT:                  count 2
+MERGE_CATS_CLS-NEXT:                   name {{.*}} myProtocol02Method
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} MyProtocol02Prop
+MERGE_CATS_CLS-NEXT:                  types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:              classMethods 0x0 (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:       optionalInstanceMethods 0x0
+MERGE_CATS_CLS-NEXT:          optionalClassMethods 0x0
+MERGE_CATS_CLS-NEXT:            instanceProperties {{.*}}
+MERGE_CATS_CLS-NEXT:               list[1] {{.*}} (struct protocol_t *)
+MERGE_CATS_CLS-NEXT:                   isa 0x0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol03
+MERGE_CATS_CLS-NEXT:             protocols 0x0
+MERGE_CATS_CLS-NEXT:           instanceMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:                entsize 24
+MERGE_CATS_CLS-NEXT:                  count 2
+MERGE_CATS_CLS-NEXT:                   name {{.*}} myProtocol03Method
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} MyProtocol03Prop
+MERGE_CATS_CLS-NEXT:                  types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:              classMethods 0x0 (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:       optionalInstanceMethods 0x0
+MERGE_CATS_CLS-NEXT:          optionalClassMethods 0x0
+MERGE_CATS_CLS-NEXT:            instanceProperties {{.*}}
+MERGE_CATS_CLS-NEXT:               list[2] {{.*}} (struct protocol_t *)
+MERGE_CATS_CLS-NEXT:                   isa 0x0
+MERGE_CATS_CLS-NEXT:                  name {{.*}} MyProtocol01
+MERGE_CATS_CLS-NEXT:             protocols 0x0
+MERGE_CATS_CLS-NEXT:           instanceMethods {{.*}} (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:                entsize 24
+MERGE_CATS_CLS-NEXT:                  count 3
+MERGE_CATS_CLS-NEXT:                   name {{.*}} myProtocol01Method
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} MyProtocol01Prop
+MERGE_CATS_CLS-NEXT:                  types {{.*}} i16@0:8
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:                   name {{.*}} setMyProtocol01Prop:
+MERGE_CATS_CLS-NEXT:                  types {{.*}} v20@0:8i16
+MERGE_CATS_CLS-NEXT:                    imp 0x0
+MERGE_CATS_CLS-NEXT:              classMethods 0x0 (struct method_list_t *)
+MERGE_CATS_CLS-NEXT:       optionalInstanceMethods 0x0
+MERGE_CATS_CLS-NEXT:          optionalClassMethods 0x0
+MERGE_CATS_CLS-NEXT:            instanceProperties {{.*}}
+MERGE_CATS_CLS-NEXT:                     ivars 0x0
+MERGE_CATS_CLS-NEXT:            weakIvarLayout 0x0
+MERGE_CATS_CLS-NEXT:            baseProperties 0x0
+MERGE_CATS_CLS:        __OBJC_$_CATEGORY_MyBaseClass_$_Category04
+
+
 #--- a64_file1.s
 
 ## @protocol MyProtocol01
diff --git a/lld/test/MachO/objc-category-merging-extern-class-minimal.s b/lld/test/MachO/objc-category-merging-minimal.s
similarity index 59%
rename from lld/test/MachO/objc-category-merging-extern-class-minimal.s
rename to lld/test/MachO/objc-category-merging-minimal.s
index 5dd8924df5ad68..fcd90f178b150e 100644
--- a/lld/test/MachO/objc-category-merging-extern-class-minimal.s
+++ b/lld/test/MachO/objc-category-merging-minimal.s
@@ -1,7 +1,8 @@
 # REQUIRES: aarch64
 # RUN: rm -rf %t; split-file %s %t && cd %t
 
-## Create a dylib with a fake base class to link against
+############ Test merging multiple categories into a single category ############
+## Create a dylib with a fake base class to link against in when merging between categories
 # RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o a64_fakedylib.o a64_fakedylib.s
 # RUN: %lld -arch arm64 a64_fakedylib.o -o a64_fakedylib.dylib -dylib
 
@@ -14,6 +15,15 @@
 # RUN: llvm-objdump --objc-meta-data --macho merge_cat_minimal_no_merge.dylib | FileCheck %s --check-prefixes=NO_MERGE_CATS
 # RUN: llvm-objdump --objc-meta-data --macho merge_cat_minimal_merge.dylib | FileCheck %s --check-prefixes=MERGE_CATS
 
+############ Test merging multiple categories into the base class ############
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o merge_base_class_minimal.o merge_base_class_minimal.s
+# RUN: %lld -arch arm64 -dylib -o merge_base_class_minimal_yes_merge.dylib -objc_category_merging merge_base_class_minimal.o merge_cat_minimal.o
+# RUN: %lld -arch arm64 -dylib -o merge_base_class_minimal_no_merge.dylib merge_base_class_minimal.o merge_cat_minimal.o
+
+# RUN: llvm-objdump --objc-meta-data --macho merge_base_class_minimal_no_merge.dylib  | FileCheck %s --check-prefixes=NO_MERGE_INTO_BASE
+# RUN: llvm-objdump --objc-meta-data --macho merge_base_class_minimal_yes_merge.dylib | FileCheck %s --check-prefixes=YES_MERGE_INTO_BASE
+
+
 #### Check merge categories enabled ###
 # Check that the original categories are not there
 MERGE_CATS-NOT: __OBJC_$_CATEGORY_MyBaseClass_$_Category01
@@ -44,6 +54,28 @@ NO_MERGE_CATS: __OBJC_$_CATEGORY_MyBaseClass_$_Category01
 NO_MERGE_CATS: __OBJC_$_CATEGORY_MyBaseClass_$_Category02
 
 
+#### Check merge cateogires into base class is disabled ####
+NO_MERGE_INTO_BASE: __OBJC_$_CATEGORY_MyBaseClass_$_Category01
+NO_MERGE_INTO_BASE: __OBJC_$_CATEGORY_MyBaseClass_$_Category02
+
+#### Check merge cateogires into base class is enabled and categories are merged into base class ####
+YES_MERGE_INTO_BASE-NOT: __OBJC_$_CATEGORY_MyBaseClass_$_Category01
+YES_MERGE_INTO_BASE-NOT: __OBJC_$_CATEGORY_MyBaseClass_$_Category02
+
+YES_MERGE_INTO_BASE: _OBJC_CLASS_$_MyBaseClass
+YES_MERGE_INTO_BASE-NEXT: _OBJC_METACLASS_$_MyBaseClass
+YES_MERGE_INTO_BASE: baseMethods
+YES_MERGE_INTO_BASE-NEXT: entsize 24
+YES_MERGE_INTO_BASE-NEXT: count 3
+YES_MERGE_INTO_BASE-NEXT: name {{.*}} cat01_InstanceMethod
+YES_MERGE_INTO_BASE-NEXT: types {{.*}} v16@0:8
+YES_MERGE_INTO_BASE-NEXT: imp -[MyBaseClass(Category01) cat01_InstanceMethod]
+YES_MERGE_INTO_BASE-NEXT: name {{.*}} cat02_InstanceMethod
+YES_MERGE_INTO_BASE-NEXT: types {{.*}} v16@0:8
+YES_MERGE_INTO_BASE-NEXT: imp -[MyBaseClass(Category02) cat02_InstanceMethod]
+YES_MERGE_INTO_BASE-NEXT: name {{.*}} baseInstanceMethod
+YES_MERGE_INTO_BASE-NEXT: types {{.*}} v16@0:8
+YES_MERGE_INTO_BASE-NEXT: imp -[MyBaseClass baseInstanceMethod]
 
 #--- a64_fakedylib.s
 
@@ -156,3 +188,94 @@ L_OBJC_IMAGE_INFO:
 
 .addrsig
 .addrsig_sym __OBJC_$_CATEGORY_MyBaseClass_$_Category01
+
+#--- merge_base_class_minimal.s
+; clang -c merge_base_class_minimal.mm -O3 -target arm64-apple-macos -arch arm64 -S -o merge_base_class_minimal.s
+;  ================== Generated from ObjC: ==================
+; __attribute__((objc_root_class))
+; @interface MyBaseClass
+; - (void)baseInstanceMethod;
+; @end
+;
+; @implementation MyBaseClass
+; - (void)baseInstanceMethod {}
+; @end
+;  ================== Generated from ObjC  ==================
+	.section	__TEXT,__text,regular,pure_instructions
+	.build_version macos, 11, 0
+	.p2align	2
+"-[MyBaseClass baseInstanceMethod]":
+	.cfi_startproc
+; %bb.0:
+	ret
+	.cfi_endproc
+	.section	__DATA,__objc_data
+	.globl	_OBJC_CLASS_$_MyBaseClass
+	.p2align	3, 0x0
+_OBJC_CLASS_$_MyBaseClass:
+	.quad	_OBJC_METACLASS_$_MyBaseClass
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	__OBJC_CLASS_RO_$_MyBaseClass
+	.globl	_OBJC_METACLASS_$_MyBaseClass
+	.p2align	3, 0x0
+_OBJC_METACLASS_$_MyBaseClass:
+	.quad	_OBJC_METACLASS_$_MyBaseClass
+	.quad	_OBJC_CLASS_$_MyBaseClass
+	.quad	0
+	.quad	0
+	.quad	__OBJC_METACLASS_RO_$_MyBaseClass
+	.section	__TEXT,__objc_classname,cstring_literals
+l_OBJC_CLASS_NAME_:
+	.asciz	"MyBaseClass"
+	.section	__DATA,__objc_const
+	.p2align	3, 0x0
+__OBJC_METACLASS_RO_$_MyBaseClass:
+	.long	3
+	.long	40
+	.long	40
+	.space	4
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.section	__TEXT,__objc_methname,cstring_literals
+l_OBJC_METH_VAR_NAME_:
+	.asciz	"baseInstanceMethod"
+	.section	__TEXT,__objc_methtype,cstring_literals
+l_OBJC_METH_VAR_TYPE_:
+	.asciz	"v16@0:8"
+	.section	__DATA,__objc_const
+	.p2align	3, 0x0
+__OBJC_$_INSTANCE_METHODS_MyBaseClass:
+	.long	24
+	.long	1
+	.quad	l_OBJC_METH_VAR_NAME_
+	.quad	l_OBJC_METH_VAR_TYPE_
+	.quad	"-[MyBaseClass baseInstanceMethod]"
+	.p2align	3, 0x0
+__OBJC_CLASS_RO_$_MyBaseClass:
+	.long	2
+	.long	0
+	.long	0
+	.space	4
+	.quad	0
+	.quad	l_OBJC_CLASS_NAME_
+	.quad	__OBJC_$_INSTANCE_METHODS_MyBaseClass
+	.quad	0
+	.quad	0
+	.quad	0
+	.quad	0
+	.section	__DATA,__objc_classlist,regular,no_dead_strip
+	.p2align	3, 0x0
+l_OBJC_LABEL_CLASS_$:
+	.quad	_OBJC_CLASS_$_MyBaseClass
+	.section	__DATA,__objc_imageinfo,regular,no_dead_strip
+L_OBJC_IMAGE_INFO:
+	.long	0
+	.long	64
+.subsections_via_symbols