diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index cc40bf2fc291..57c6cd9171aa 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -4768,6 +4768,26 @@ def CIR_EhSetjmpOp : CIR_Op<"eh.setjmp"> {
   }];
 }
 
+def CIR_EhLongjmpOp : CIR_Op<"eh.longjmp"> {
+  let summary = "CIR longjmp operation";
+  let description = [{
+    Restore the environment (e.g., stack pointer, instruction pointer,
+    signal mask, and other registers) at the time of setjmp() call, by using
+    the information saved in `env` by setjmp().
+
+    Examples:
+    ```mlir
+      cir.eh.longjmp %arg0 : !cir.ptr<!cir.void>
+    ```
+  }];
+
+  let arguments = (ins CIR_PointerType:$env);
+
+  let assemblyFormat = [{
+      $env `:` qualified(type($env)) attr-dict
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // CopyOp
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
index 192f2233fcd8..62520ca17107 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
@@ -1963,8 +1963,14 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
         cir::EhSetjmpOp::create(builder, loc, castBuf, /*is_builtin=*/true);
     return RValue::get(op);
   }
-  case Builtin::BI__builtin_longjmp:
-    llvm_unreachable("BI__builtin_longjmp NYI");
+  case Builtin::BI__builtin_longjmp: {
+    mlir::Value buf = emitScalarExpr(E->getArg(0));
+    mlir::Location loc = getLoc(E->getExprLoc());
+
+    cir::EhLongjmpOp::create(builder, loc, buf);
+    builder.create<cir::UnreachableOp>(loc);
+    return RValue::get(nullptr);
+  }
   case Builtin::BI__builtin_launder: {
     const clang::Expr *arg = E->getArg(0);
     clang::QualType argTy = arg->getType()->getPointeeType();
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index 21b17142d8fe..7798ee5093bb 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -4331,6 +4331,14 @@ mlir::LogicalResult CIRToLLVMEhSetjmpOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMEhLongjmpOpLowering::matchAndRewrite(
+    cir::EhLongjmpOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  replaceOpWithCallLLVMIntrinsicOp(rewriter, op, "llvm.eh.sjlj.longjmp",
+                                   /*resultTy=*/{}, adaptor.getOperands());
+  return mlir::success();
+}
+
 mlir::LogicalResult CIRToLLVMCatchParamOpLowering::matchAndRewrite(
     cir::CatchParamOp op, OpAdaptor adaptor,
     mlir::ConversionPatternRewriter &rewriter) const {
@@ -4635,6 +4643,7 @@ void populateCIRToLLVMConversionPatterns(
       CIRToLLVMEhInflightOpLowering,
       CIRToLLVMEhTypeIdOpLowering,
       CIRToLLVMEhSetjmpOpLowering,
+      CIRToLLVMEhLongjmpOpLowering,
       CIRToLLVMExpectOpLowering,
       CIRToLLVMExtractMemberOpLowering,
       CIRToLLVMFrameAddrOpLowering,
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
index f13c37106665..445249311996 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
@@ -1273,6 +1273,16 @@ class CIRToLLVMEhSetjmpOpLowering
                   mlir::ConversionPatternRewriter &) const override;
 };
 
+class CIRToLLVMEhLongjmpOpLowering
+    : public mlir::OpConversionPattern<cir::EhLongjmpOp> {
+public:
+  using mlir::OpConversionPattern<cir::EhLongjmpOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(cir::EhLongjmpOp op, OpAdaptor,
+                  mlir::ConversionPatternRewriter &) const override;
+};
+
 class CIRToLLVMCatchParamOpLowering
     : public mlir::OpConversionPattern<cir::CatchParamOp> {
 public:
diff --git a/clang/test/CIR/CodeGen/builtin-setjmp-longjmp.c b/clang/test/CIR/CodeGen/builtin-setjmp-longjmp.c
index b63f3a75da5a..2d96139c347f 100644
--- a/clang/test/CIR/CodeGen/builtin-setjmp-longjmp.c
+++ b/clang/test/CIR/CodeGen/builtin-setjmp-longjmp.c
@@ -61,3 +61,24 @@ void test_setjmp2(void *env) {
   // OGCG: call i32 @_setjmp(ptr noundef [[ENV]])
   _setjmp (env);
 }
+
+void test_longjmp(void *env) {
+  // CIR-LABEL: test_longjmp
+  // CIR-SAME: [[ENV:%.*]]: 
+  // CIR-NEXT: [[ENV_ALLOCA:%[0-9]+]] = cir.alloca !cir.ptr<!void>, !cir.ptr<!cir.ptr<!void>>,
+  // CIR-NEXT: cir.store [[ENV]], [[ENV_ALLOCA]] : !cir.ptr<!void>, !cir.ptr<!cir.ptr<!void>>
+  // CIR-NEXT: [[ENV_LOAD:%[0-9]+]] = cir.load align(8) [[ENV_ALLOCA]]
+  // CIR-NEXT: [[CAST:%[0-9]+]] = cir.cast bitcast [[ENV_LOAD]] : !cir.ptr<!void> -> !cir.ptr<!cir.ptr<!void>>
+  // CIR-NEXT: cir.eh.longjmp [[CAST]] : !cir.ptr<!cir.ptr<!void>>
+  // CIR-NEXT: cir.unreachable
+
+
+  // LLVM-LABEL: test_longjmp
+  // LLVM: @llvm.eh.sjlj.longjmp
+  // LLVM-NEXT: unreachable
+  
+  // OGCG-LABEL: test_longjmp
+  // OGCG: @llvm.eh.sjlj.longjmp
+  // OGCG-NEXT: unreachable
+  __builtin_longjmp(env, 1);
+}
diff --git a/clang/test/CIR/Lowering/setjmp-longjmp.cir b/clang/test/CIR/Lowering/setjmp-longjmp.cir
index 627a573e5051..1a441ce494e0 100644
--- a/clang/test/CIR/Lowering/setjmp-longjmp.cir
+++ b/clang/test/CIR/Lowering/setjmp-longjmp.cir
@@ -23,6 +23,15 @@ module {
     %0 = cir.eh.setjmp %arg0 : (!p32) -> !s32i
     cir.return %0 : !s32i
   }
+  cir.func @test_longjmp(%arg0 : !p32) {
+
+    // MLIR: llvm.func @test_longjmp([[ARG0:%.*]]: !llvm.ptr)
+    // MLIR-NEXT:    llvm.call_intrinsic "llvm.eh.sjlj.longjmp"([[ARG0]]) : (!llvm.ptr) -> ()
+    // MLIR-NEXT:    llvm.unreachable
+    // MLIR-NEXT:  }
+    cir.eh.longjmp %arg0 : !p32
+    cir.unreachable
+  }
   // MLIR: }
 }
 
diff --git a/clang/test/CIR/Transforms/setjmp-longjmp-lower.c b/clang/test/CIR/Transforms/setjmp-longjmp-lower.c
index 883e3d6a0bf2..33b4643eb081 100644
--- a/clang/test/CIR/Transforms/setjmp-longjmp-lower.c
+++ b/clang/test/CIR/Transforms/setjmp-longjmp-lower.c
@@ -52,3 +52,23 @@ void test_setjmp2(void *env) {
   // AFTER-LOWERING-PREPARE-NEXT: cir.eh.setjmp [[CAST]] : (!cir.ptr<!cir.ptr<!void>>) -> !s32i
   _setjmp (env);
 }
+void test_longjmp(void *env) {
+  // BEFORE-LOWERING-PREPARE-LABEL: test_longjmp
+  // BEFORE-LOWERING-PREPARE-SAME: [[ENV:%.*]]:
+  // BEFORE-LOWERING-PREPARE-NEXT: [[ENV_ALLOCA:%.*]] = cir.alloca
+  // BEFORE-LOWERING-PREPARE-NEXT: cir.store [[ENV]], [[ENV_ALLOCA]]
+  // BEFORE-LOWERING-PREPARE-NEXT: [[ENV_LOAD:%.*]] = cir.load align(8) [[ENV_ALLOCA]]
+  // BEFORE-LOWERING-PREPARE-NEXT: [[CAST:%.*]] = cir.cast bitcast [[ENV_LOAD]]
+  // BEFORE-LOWERING-PREPARE-NEXT: cir.eh.longjmp [[CAST]] : !cir.ptr<!cir.ptr<!void>>
+  // BEFORE-LOWERING-PREPARE-NEXT: cir.unreachable
+
+  // AFTER-LOWERING-PREPARE-LABEL: test_longjmp
+  // AFTER-LOWERING-PREPARE-SAME: [[ENV:%.*]]:
+  // AFTER-LOWERING-PREPARE-NEXT: [[ENV_ALLOCA:%.*]] = cir.alloca
+  // AFTER-LOWERING-PREPARE-NEXT: cir.store [[ENV]], [[ENV_ALLOCA]]
+  // AFTER-LOWERING-PREPARE-NEXT: [[ENV_LOAD:%.*]] = cir.load align(8) [[ENV_ALLOCA]]
+  // AFTER-LOWERING-PREPARE-NEXT: [[CAST:%.*]] = cir.cast bitcast [[ENV_LOAD]]
+  // AFTER-LOWERING-PREPARE-NEXT: cir.eh.longjmp [[CAST]] : !cir.ptr<!cir.ptr<!void>>
+  // AFTER-LOWERING-PREPARE-NEXT: cir.unreachable
+  __builtin_longjmp(env, 1);
+}