diff --git a/clang/include/clang/Tooling/AllTUsExecution.h b/clang/include/clang/Tooling/AllTUsExecution.h
--- a/clang/include/clang/Tooling/AllTUsExecution.h
+++ b/clang/include/clang/Tooling/AllTUsExecution.h
@@ -44,8 +44,6 @@
 
   StringRef getExecutorName() const override { return ExecutorName; }
 
-  bool isSingleProcess() const override { return true; }
-
   using ToolExecutor::execute;
 
   llvm::Error
diff --git a/clang/include/clang/Tooling/Execution.h b/clang/include/clang/Tooling/Execution.h
--- a/clang/include/clang/Tooling/Execution.h
+++ b/clang/include/clang/Tooling/Execution.h
@@ -115,13 +115,6 @@
   /// Returns the name of a specific executor.
   virtual StringRef getExecutorName() const = 0;
 
-  /// Should return true iff executor runs all actions in a single process.
-  /// Clients can use this signal to find out if they can collect results
-  /// in-memory (e.g. to avoid serialization costs of using ToolResults).
-  /// The single-process executors can still run multiple threads, but all
-  /// executions are guaranteed to share the same memory.
-  virtual bool isSingleProcess() const = 0;
-
   /// Executes each action with a corresponding arguments adjuster.
   virtual llvm::Error
   execute(llvm::ArrayRef<
diff --git a/clang/include/clang/Tooling/StandaloneExecution.h b/clang/include/clang/Tooling/StandaloneExecution.h
--- a/clang/include/clang/Tooling/StandaloneExecution.h
+++ b/clang/include/clang/Tooling/StandaloneExecution.h
@@ -52,8 +52,6 @@
 
   StringRef getExecutorName() const override { return ExecutorName; }
 
-  bool isSingleProcess() const override { return true; }
-
   using ToolExecutor::execute;
 
   llvm::Error
diff --git a/clang/unittests/Tooling/ExecutionTest.cpp b/clang/unittests/Tooling/ExecutionTest.cpp
--- a/clang/unittests/Tooling/ExecutionTest.cpp
+++ b/clang/unittests/Tooling/ExecutionTest.cpp
@@ -95,8 +95,6 @@
 
   StringRef getExecutorName() const override { return ExecutorName; }
 
-  bool isSingleProcess() const override { return true; }
-
   llvm::Error
   execute(llvm::ArrayRef<std::pair<std::unique_ptr<FrontendActionFactory>,
                                    ArgumentsAdjuster>>) override {