diff --git a/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp b/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
index 06c0af5445d5d..0e43480e82926 100644
--- a/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
+++ b/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
@@ -725,6 +725,20 @@ struct LLVMInlinerInterface : public DialectInlinerInterface {
           }))
         return false;
     }
+    // Refuse to inline if any block in the callee ends with an op that does
+    // not have the terminator trait. The MLIR verifier conservatively accepts
+    // unregistered ops as potential terminators (via mightHaveTrait), but
+    // handleTerminator uses cast<LLVM::ReturnOp> in the single-block path and
+    // would crash on such ops. Registered terminators from other dialects
+    // (e.g. cf.br) are safe: the multi-block path uses dyn_cast and skips
+    // non-llvm.return ops gracefully.
+    for (Block &block : funcOp.getBody()) {
+      if (!block.empty() && !block.back().hasTrait<OpTrait::IsTerminator>()) {
+        LDBG() << "Cannot inline " << funcOp.getSymName()
+               << ": block ends with non-terminator op";
+        return false;
+      }
+    }
     return true;
   }
 
diff --git a/mlir/test/Dialect/LLVMIR/inlining.mlir b/mlir/test/Dialect/LLVMIR/inlining.mlir
index 9a77c5e223110..70ce7ca20986b 100644
--- a/mlir/test/Dialect/LLVMIR/inlining.mlir
+++ b/mlir/test/Dialect/LLVMIR/inlining.mlir
@@ -709,3 +709,42 @@ func.func @llvm_ret(%arg0 : i32) -> i32 {
   // CHECK: return %[[R]]
   return %res : i32
 }
+
+// -----
+// Regression test for https://github.com/llvm/llvm-project/issues/118766
+// A callee whose body block ends with an unregistered (non-terminator) op used
+// to crash the inliner. The inliner should skip such callees instead.
+
+llvm.func @callee_malformed_terminator() -> i64 attributes {llvm.emit_c_interface} {
+  // Unregistered op acting as a fake terminator -- the function has no llvm.return.
+  "test.foo"() : () -> ()
+}
+
+// CHECK-LABEL: @caller_malformed_terminator
+llvm.func @caller_malformed_terminator() -> i64 attributes {llvm.emit_c_interface} {
+  // CHECK: llvm.call @callee_malformed_terminator
+  %0 = llvm.call @callee_malformed_terminator() : () -> i64
+  llvm.return %0 : i64
+}
+
+// -----
+// Complement to the above: a callee whose block ends with a registered
+// non-LLVM terminator that genuinely has the IsTerminator trait (cf.br) does
+// NOT trigger the guard. The call is inlined normally via the multi-block path
+// (handleTerminator uses dyn_cast for non-llvm.return ops, so cf.br is left
+// as-is and control flow reaches the llvm.return in the successor block).
+
+llvm.func @callee_cf_br_terminator(%arg0 : i64) -> i64 {
+  cf.br ^exit(%arg0 : i64)
+^exit(%val : i64):
+  llvm.return %val : i64
+}
+
+// CHECK-LABEL: @caller_cf_br_terminator
+llvm.func @caller_cf_br_terminator(%arg0 : i64) -> i64 {
+  // cf.br has IsTerminator, so isLegalToInline allows inlining.
+  // CHECK-NOT: llvm.call @callee_cf_br_terminator
+  // CHECK: llvm.return %arg0
+  %0 = llvm.call @callee_cf_br_terminator(%arg0) : (i64) -> i64
+  llvm.return %0 : i64
+}