diff --git a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
index 01a16e7c7b1e5..f6888d001fed6 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -778,6 +778,7 @@ class TargetTransformInfoImplBase {
     case Intrinsic::experimental_gc_relocate:
     case Intrinsic::coro_alloc:
     case Intrinsic::coro_begin:
+    case Intrinsic::coro_begin_custom_abi:
     case Intrinsic::coro_free:
     case Intrinsic::coro_end:
     case Intrinsic::coro_frame:
diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
index 20dd921ddbd23..8a0721cf23f53 100644
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -1719,7 +1719,8 @@ def int_coro_prepare_async : Intrinsic<[llvm_ptr_ty], [llvm_ptr_ty],
                                        [IntrNoMem]>;
 def int_coro_begin : Intrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_ptr_ty],
                                [WriteOnly<ArgIndex<1>>]>;
-
+def int_coro_begin_custom_abi : Intrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_ptr_ty, llvm_i32_ty],
+                               [WriteOnly<ArgIndex<1>>]>;
 def int_coro_free : Intrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_ptr_ty],
                               [IntrReadMem, IntrArgMemOnly,
                                ReadOnly<ArgIndex<1>>,
diff --git a/llvm/include/llvm/Transforms/Coroutines/ABI.h b/llvm/include/llvm/Transforms/Coroutines/ABI.h
index e7568d275c161..8b83c5308056e 100644
--- a/llvm/include/llvm/Transforms/Coroutines/ABI.h
+++ b/llvm/include/llvm/Transforms/Coroutines/ABI.h
@@ -29,7 +29,13 @@ namespace coro {
 // This interface/API is to provide an object oriented way to implement ABI
 // functionality. This is intended to replace use of the ABI enum to perform
 // ABI operations. The ABIs (e.g. Switch, Async, Retcon{Once}) are the common
-// ABIs.
+// ABIs. However, specific users may need to modify the behavior of these. This
+// can be accomplished by inheriting one of the common ABIs and overriding one
+// or more of the methods to create a custom ABI. To use a custom ABI for a
+// given coroutine the coro.begin.custom.abi intrinsic is used in place of the
+// coro.begin intrinsic. This takes an additional i32 arg that specifies the
+// index of an ABI generator for the custom ABI object in a SmallVector passed
+// to CoroSplitPass ctor.
 
 class BaseABI {
 public:
diff --git a/llvm/include/llvm/Transforms/Coroutines/CoroInstr.h b/llvm/include/llvm/Transforms/Coroutines/CoroInstr.h
index a329a06bf1389..3aa30bec85c3a 100644
--- a/llvm/include/llvm/Transforms/Coroutines/CoroInstr.h
+++ b/llvm/include/llvm/Transforms/Coroutines/CoroInstr.h
@@ -124,7 +124,8 @@ class AnyCoroIdInst : public IntrinsicInst {
   IntrinsicInst *getCoroBegin() {
     for (User *U : users())
       if (auto *II = dyn_cast<IntrinsicInst>(U))
-        if (II->getIntrinsicID() == Intrinsic::coro_begin)
+        if (II->getIntrinsicID() == Intrinsic::coro_begin ||
+            II->getIntrinsicID() == Intrinsic::coro_begin_custom_abi)
           return II;
     llvm_unreachable("no coro.begin associated with coro.id");
   }
@@ -442,20 +443,30 @@ class CoroFreeInst : public IntrinsicInst {
   }
 };
 
-/// This class represents the llvm.coro.begin instructions.
+/// This class represents the llvm.coro.begin or llvm.coro.begin.custom.abi
+/// instructions.
 class CoroBeginInst : public IntrinsicInst {
-  enum { IdArg, MemArg };
+  enum { IdArg, MemArg, CustomABIArg };
 
 public:
   AnyCoroIdInst *getId() const {
     return cast<AnyCoroIdInst>(getArgOperand(IdArg));
   }
 
+  bool hasCustomABI() const {
+    return getIntrinsicID() == Intrinsic::coro_begin_custom_abi;
+  }
+
+  int getCustomABI() const {
+    return cast<ConstantInt>(getArgOperand(CustomABIArg))->getZExtValue();
+  }
+
   Value *getMem() const { return getArgOperand(MemArg); }
 
   // Methods for support type inquiry through isa, cast, and dyn_cast:
   static bool classof(const IntrinsicInst *I) {
-    return I->getIntrinsicID() == Intrinsic::coro_begin;
+    return I->getIntrinsicID() == Intrinsic::coro_begin ||
+           I->getIntrinsicID() == Intrinsic::coro_begin_custom_abi;
   }
   static bool classof(const Value *V) {
     return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
diff --git a/llvm/include/llvm/Transforms/Coroutines/CoroSplit.h b/llvm/include/llvm/Transforms/Coroutines/CoroSplit.h
index a5fd57f8f9dfa..6c6a982e82805 100644
--- a/llvm/include/llvm/Transforms/Coroutines/CoroSplit.h
+++ b/llvm/include/llvm/Transforms/Coroutines/CoroSplit.h
@@ -28,17 +28,26 @@ struct Shape;
 } // namespace coro
 
 struct CoroSplitPass : PassInfoMixin<CoroSplitPass> {
+  using BaseABITy =
+      std::function<std::unique_ptr<coro::BaseABI>(Function &, coro::Shape &)>;
 
   CoroSplitPass(bool OptimizeFrame = false);
+
+  CoroSplitPass(SmallVector<BaseABITy> GenCustomABIs,
+                bool OptimizeFrame = false);
+
   CoroSplitPass(std::function<bool(Instruction &)> MaterializableCallback,
                 bool OptimizeFrame = false);
 
+  CoroSplitPass(std::function<bool(Instruction &)> MaterializableCallback,
+                SmallVector<BaseABITy> GenCustomABIs,
+                bool OptimizeFrame = false);
+
   PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
                         LazyCallGraph &CG, CGSCCUpdateResult &UR);
+
   static bool isRequired() { return true; }
 
-  using BaseABITy =
-      std::function<std::unique_ptr<coro::BaseABI>(Function &, coro::Shape &)>;
   // Generator for an ABI transformer
   BaseABITy CreateAndInitABI;
 
diff --git a/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp b/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp
index dd92b3593af92..1cda7f93f72a2 100644
--- a/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp
@@ -53,6 +53,7 @@ bool Lowerer::lower(Function &F) {
       default:
         continue;
       case Intrinsic::coro_begin:
+      case Intrinsic::coro_begin_custom_abi:
         II->replaceAllUsesWith(II->getArgOperand(1));
         break;
       case Intrinsic::coro_free:
@@ -112,7 +113,8 @@ static bool declaresCoroCleanupIntrinsics(const Module &M) {
       M, {"llvm.coro.alloc", "llvm.coro.begin", "llvm.coro.subfn.addr",
           "llvm.coro.free", "llvm.coro.id", "llvm.coro.id.retcon",
           "llvm.coro.id.async", "llvm.coro.id.retcon.once",
-          "llvm.coro.async.size.replace", "llvm.coro.async.resume"});
+          "llvm.coro.async.size.replace", "llvm.coro.async.resume",
+          "llvm.coro.begin.custom.abi"});
 }
 
 PreservedAnalyses CoroCleanupPass::run(Module &M,
diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index ef1f27118bc14..88ce331c8cfb6 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -2200,7 +2200,15 @@ static void addPrepareFunction(const Module &M,
 
 static std::unique_ptr<coro::BaseABI>
 CreateNewABI(Function &F, coro::Shape &S,
-             std::function<bool(Instruction &)> IsMatCallback) {
+             std::function<bool(Instruction &)> IsMatCallback,
+             const SmallVector<CoroSplitPass::BaseABITy> GenCustomABIs) {
+  if (S.CoroBegin->hasCustomABI()) {
+    unsigned CustomABI = S.CoroBegin->getCustomABI();
+    if (CustomABI >= GenCustomABIs.size())
+      llvm_unreachable("Custom ABI not found amoung those specified");
+    return GenCustomABIs[CustomABI](F, S);
+  }
+
   switch (S.ABI) {
   case coro::ABI::Switch:
     return std::unique_ptr<coro::BaseABI>(
@@ -2221,7 +2229,17 @@ CreateNewABI(Function &F, coro::Shape &S,
 CoroSplitPass::CoroSplitPass(bool OptimizeFrame)
     : CreateAndInitABI([](Function &F, coro::Shape &S) {
         std::unique_ptr<coro::BaseABI> ABI =
-            CreateNewABI(F, S, coro::isTriviallyMaterializable);
+            CreateNewABI(F, S, coro::isTriviallyMaterializable, {});
+        ABI->init();
+        return ABI;
+      }),
+      OptimizeFrame(OptimizeFrame) {}
+
+CoroSplitPass::CoroSplitPass(
+    SmallVector<CoroSplitPass::BaseABITy> GenCustomABIs, bool OptimizeFrame)
+    : CreateAndInitABI([=](Function &F, coro::Shape &S) {
+        std::unique_ptr<coro::BaseABI> ABI =
+            CreateNewABI(F, S, coro::isTriviallyMaterializable, GenCustomABIs);
         ABI->init();
         return ABI;
       }),
@@ -2232,7 +2250,21 @@ CoroSplitPass::CoroSplitPass(bool OptimizeFrame)
 CoroSplitPass::CoroSplitPass(std::function<bool(Instruction &)> IsMatCallback,
                              bool OptimizeFrame)
     : CreateAndInitABI([=](Function &F, coro::Shape &S) {
-        std::unique_ptr<coro::BaseABI> ABI = CreateNewABI(F, S, IsMatCallback);
+        std::unique_ptr<coro::BaseABI> ABI =
+            CreateNewABI(F, S, IsMatCallback, {});
+        ABI->init();
+        return ABI;
+      }),
+      OptimizeFrame(OptimizeFrame) {}
+
+// For back compatibility, constructor takes a materializable callback and
+// creates a generator for an ABI with a modified materializable callback.
+CoroSplitPass::CoroSplitPass(
+    std::function<bool(Instruction &)> IsMatCallback,
+    SmallVector<CoroSplitPass::BaseABITy> GenCustomABIs, bool OptimizeFrame)
+    : CreateAndInitABI([=](Function &F, coro::Shape &S) {
+        std::unique_ptr<coro::BaseABI> ABI =
+            CreateNewABI(F, S, IsMatCallback, GenCustomABIs);
         ABI->init();
         return ABI;
       }),
diff --git a/llvm/lib/Transforms/Coroutines/Coroutines.cpp b/llvm/lib/Transforms/Coroutines/Coroutines.cpp
index f4d9a7a8aa856..1c45bcd7f6a83 100644
--- a/llvm/lib/Transforms/Coroutines/Coroutines.cpp
+++ b/llvm/lib/Transforms/Coroutines/Coroutines.cpp
@@ -73,6 +73,7 @@ static const char *const CoroIntrinsics[] = {
     "llvm.coro.await.suspend.handle",
     "llvm.coro.await.suspend.void",
     "llvm.coro.begin",
+    "llvm.coro.begin.custom.abi",
     "llvm.coro.destroy",
     "llvm.coro.done",
     "llvm.coro.end",
@@ -247,7 +248,8 @@ void coro::Shape::analyze(Function &F,
         }
         break;
       }
-      case Intrinsic::coro_begin: {
+      case Intrinsic::coro_begin:
+      case Intrinsic::coro_begin_custom_abi: {
         auto CB = cast<CoroBeginInst>(II);
 
         // Ignore coro id's that aren't pre-split.
diff --git a/llvm/unittests/Transforms/Coroutines/ExtraRematTest.cpp b/llvm/unittests/Transforms/Coroutines/ExtraRematTest.cpp
index 1d55889a32d7a..c3394fdaa940b 100644
--- a/llvm/unittests/Transforms/Coroutines/ExtraRematTest.cpp
+++ b/llvm/unittests/Transforms/Coroutines/ExtraRematTest.cpp
@@ -182,4 +182,91 @@ TEST_F(ExtraRematTest, TestCoroRematWithCallback) {
   CallInst *CI = getCallByName(Resume1, "should.remat");
   ASSERT_TRUE(CI);
 }
+
+StringRef TextCoroBeginCustomABI = R"(
+    define ptr @f(i32 %n) presplitcoroutine {
+    entry:
+      %id = call token @llvm.coro.id(i32 0, ptr null, ptr null, ptr null)
+      %size = call i32 @llvm.coro.size.i32()
+      %alloc = call ptr @malloc(i32 %size)
+      %hdl = call ptr @llvm.coro.begin.custom.abi(token %id, ptr %alloc, i32 0)
+
+      %inc1 = add i32 %n, 1
+      %val2 = call i32 @should.remat(i32 %inc1)
+      %sp1 = call i8 @llvm.coro.suspend(token none, i1 false)
+      switch i8 %sp1, label %suspend [i8 0, label %resume1
+                                      i8 1, label %cleanup]
+    resume1:
+      %inc2 = add i32 %val2, 1
+      %sp2 = call i8 @llvm.coro.suspend(token none, i1 false)
+      switch i8 %sp1, label %suspend [i8 0, label %resume2
+                                      i8 1, label %cleanup]
+
+    resume2:
+      call void @print(i32 %val2)
+      call void @print(i32 %inc2)
+      br label %cleanup
+
+    cleanup:
+      %mem = call ptr @llvm.coro.free(token %id, ptr %hdl)
+      call void @free(ptr %mem)
+      br label %suspend
+    suspend:
+      call i1 @llvm.coro.end(ptr %hdl, i1 0)
+      ret ptr %hdl
+    }
+
+    declare ptr @llvm.coro.free(token, ptr)
+    declare i32 @llvm.coro.size.i32()
+    declare i8  @llvm.coro.suspend(token, i1)
+    declare void @llvm.coro.resume(ptr)
+    declare void @llvm.coro.destroy(ptr)
+
+    declare token @llvm.coro.id(i32, ptr, ptr, ptr)
+    declare i1 @llvm.coro.alloc(token)
+    declare ptr @llvm.coro.begin.custom.abi(token, ptr, i32)
+    declare i1 @llvm.coro.end(ptr, i1)
+
+    declare i32 @should.remat(i32)
+
+    declare noalias ptr @malloc(i32)
+    declare void @print(i32)
+    declare void @free(ptr)
+  )";
+
+// SwitchABI with overridden isMaterializable
+class ExtraCustomABI : public coro::SwitchABI {
+public:
+  ExtraCustomABI(Function &F, coro::Shape &S)
+      : coro::SwitchABI(F, S, ExtraMaterializable) {}
+};
+
+TEST_F(ExtraRematTest, TestCoroRematWithCustomABI) {
+  ParseAssembly(TextCoroBeginCustomABI);
+
+  ASSERT_TRUE(M);
+
+  CoroSplitPass::BaseABITy GenCustomABI = [](Function &F, coro::Shape &S) {
+    return std::unique_ptr<coro::BaseABI>(new ExtraCustomABI(F, S));
+  };
+
+  CGSCCPassManager CGPM;
+  CGPM.addPass(CoroSplitPass({GenCustomABI}));
+  MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(std::move(CGPM)));
+  MPM.run(*M, MAM);
+
+  // Verify that extra rematerializable instruction has been rematerialized
+  Function *F = M->getFunction("f.resume");
+  ASSERT_TRUE(F) << "could not find split function f.resume";
+
+  BasicBlock *Resume1 = getBasicBlockByName(F, "resume1");
+  ASSERT_TRUE(Resume1)
+      << "could not find expected BB resume1 in split function";
+
+  // With callback the extra rematerialization of the function should have
+  // happened
+  CallInst *CI = getCallByName(Resume1, "should.remat");
+  ASSERT_TRUE(CI);
+}
+
 } // namespace