diff --git a/llvm/test/CAS/emit-casid-file.ll b/llvm/test/CAS/emit-casid-file.ll
new file mode 100644
index 0000000000000..317e838d32e91
--- /dev/null
+++ b/llvm/test/CAS/emit-casid-file.ll
@@ -0,0 +1,49 @@
+; RUN: rm -rf %t && mkdir -p %t
+; RUN: llc -O0 -cas-friendly-debug-info --filetype=obj --cas-backend --cas=/tmp/cas --mccas-native %s --mccas-emit-casid-file -o %t/test.o
+; RUN: cat %t/test.o.casid | FileCheck %s --check-prefix=NATIVE_FILENAME
+; NATIVE_FILENAME: CASID:Jllvmcas://{{.*}}
+;
+; RUN: rm -rf %t && mkdir -p %t
+; RUN: llc -O0 -cas-friendly-debug-info --filetype=obj --cas-backend --cas=/tmp/cas --mccas-verify %s --mccas-emit-casid-file -o %t/test.o
+; RUN: cat %t/test.o.casid | FileCheck %s --check-prefix=VERIFY_FILENAME
+; VERIFY_FILENAME: CASID:Jllvmcas://{{.*}}
+;
+; RUN: rm -rf %t && mkdir -p %t
+; RUN: llc -O0 -cas-friendly-debug-info --filetype=obj --cas-backend --cas=/tmp/cas --mccas-casid %s --mccas-emit-casid-file -o %t/test.o
+; RUN: not cat %t/test.o.casid
+;
+; RUN: rm -rf %t && mkdir -p %t
+; RUN: llc -O0 -cas-friendly-debug-info --filetype=obj --cas-backend --cas=/tmp/cas --mccas-native %s --mccas-emit-casid-file -o -
+; RUN: not cat %t/test.o.casid
+;
+; RUN: rm -rf %t && mkdir -p %t
+; RUN: llc -O0 -cas-friendly-debug-info --filetype=obj --cas-backend --cas=/tmp/cas --mccas-verify %s --mccas-emit-casid-file -o -
+; RUN: not cat %t/test.o.casid
+;
+; RUN: rm -rf %t && mkdir -p %t
+; RUN: llc -O0 -cas-friendly-debug-info --filetype=obj --cas-backend --cas=/tmp/cas --mccas-casid %s --mccas-emit-casid-file -o -
+; RUN: not cat %t/test.o.casid
+
+; ModuleID = '/Users/shubham/Development/test109275485/a.cpp'
+source_filename = "/Users/shubham/Development/test109275485/a.cpp"
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+target triple = "arm64-apple-macosx14.0.0"
+
+; Function Attrs: mustprogress noinline nounwind optnone ssp uwtable(sync)
+define noundef i32 @_Z3fooi(i32 noundef %x) #0 {
+entry:
+  %x.addr = alloca i32, align 4
+  store i32 %x, ptr %x.addr, align 4
+  %0 = load i32, ptr %x.addr, align 4
+  %add = add nsw i32 %0, 2
+  ret i32 %add
+}
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+!llvm.ident = !{!4}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 8, !"PIC Level", i32 2}
+!2 = !{i32 7, !"uwtable", i32 1}
+!3 = !{i32 7, !"frame-pointer", i32 1}
+!4 = !{!"clang version 18.0.0 (git@github.com:apple/llvm-project.git bd5fc55041b3dfab2de1640638ce4b5e8a016998)"}
diff --git a/llvm/tools/llc/llc.cpp b/llvm/tools/llc/llc.cpp
index 9edc09b778b74..28d88b18da7d6 100644
--- a/llvm/tools/llc/llc.cpp
+++ b/llvm/tools/llc/llc.cpp
@@ -202,6 +202,12 @@ static cl::opt<CASBackendMode> MCCASBackendMode(
                           "Native object without verifier"),
                clEnumValN(CASBackendMode::CASID, "mccas-casid",
                           "CASID file output")));
+
+static cl::opt<bool>
+    EmitCASIDFile("mccas-emit-casid-file",
+                  cl::desc("Emit a .casid file next to the generated .o file "
+                           "when MC CAS is enabled"),
+                  cl::init(false));
 // END MCCAS
 
 namespace {
@@ -694,6 +700,23 @@ static int compileModule(char **argv, LLVMContext &Context) {
   // Ensure the filename is passed down to CodeViewDebug.
   Target->Options.ObjectFilenameForDebug = Out->outputFilename();
 
+  std::unique_ptr<ToolOutputFile> CasIDOS;
+  std::string OutputPathCASIDFile;
+  StringRef OutputFile = StringRef(Out->outputFilename());
+  if (UseMCCASBackend && EmitCASIDFile &&
+      MCCASBackendMode != CASBackendMode::CASID &&
+      codegen::getFileType() == CGFT_ObjectFile && OutputFile != "-") {
+    OutputPathCASIDFile = std::string(OutputFile);
+    OutputPathCASIDFile.append(".casid");
+    std::error_code EC;
+    CasIDOS = std::make_unique<ToolOutputFile>(OutputPathCASIDFile, EC,
+                                               sys::fs::OF_None);
+    if (EC) {
+      reportError(EC.message());
+      return 1;
+    }
+  }
+
   std::unique_ptr<ToolOutputFile> DwoOut;
   if (!SplitDwarfOutputFile.empty()) {
     std::error_code EC;
@@ -779,7 +802,8 @@ static int compileModule(char **argv, LLVMContext &Context) {
       PM.add(createFreeMachineFunctionPass());
     } else if (Target->addPassesToEmitFile(
                    PM, *OS, DwoOut ? &DwoOut->os() : nullptr,
-                   codegen::getFileType(), NoVerify, MMIWP)) {
+                   codegen::getFileType(), NoVerify, MMIWP,
+                   CasIDOS ? &CasIDOS->os() : nullptr)) {
       reportError("target does not support generation of this file type");
     }
 
@@ -838,6 +862,8 @@ static int compileModule(char **argv, LLVMContext &Context) {
   Out->keep();
   if (DwoOut)
     DwoOut->keep();
+  if (CasIDOS)
+    CasIDOS->keep();
 
   return 0;
 }