diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1314,6 +1314,10 @@
       BitcodeEmbed = static_cast<BitcodeEmbedMode>(Model);
   }
 
+  // Remove existing compilation database so that each job can append to it.
+  if (Arg *A = Args.getLastArg(options::OPT_MJ))
+    llvm::sys::fs::remove(A->getValue());
+
   // Setting up the jobs for some precompile cases depends on whether we are
   // treating them as PCH, implicit modules or C++20 ones.
   // TODO: inferring the mode like this seems fragile (it meets the objective
diff --git a/clang/test/Driver/compilation_database_multiarch.c b/clang/test/Driver/compilation_database_multiarch.c
--- a/clang/test/Driver/compilation_database_multiarch.c
+++ b/clang/test/Driver/compilation_database_multiarch.c
@@ -2,7 +2,14 @@
 
 // RUN: rm -rf %t && mkdir -p %t
 // RUN: %clang -fdriver-only -o %t/out %s -mtargetos=macos12 -arch arm64 -arch x86_64 -MJ %t/compilation_database.json
+
+// Let's run that again and verify we're not accumulating redundant entries in the same file.
+//
+// RUN: %clang -fdriver-only -o %t/out %s -mtargetos=macos12 -arch arm64 -arch x86_64 -MJ %t/compilation_database.json
+// RUN: echo EOF >> %t/compilation_database.json
+
 // RUN: FileCheck --input-file=%t/compilation_database.json %s
 
 // CHECK:      { "directory": "{{.*}}", "file": "{{.*}}", "output": "[[OUTPUT_X86_64:.*]]", "arguments": [{{.*}}, "-o", "[[OUTPUT_X86_64]]", {{.*}} "--target=x86_64-apple-macosx12.0.0"]},
 // CHECK-NEXT: { "directory": "{{.*}}", "file": "{{.*}}", "output": "[[OUTPUT_ARM64:.*]]", "arguments": [{{.*}}, "-o", "[[OUTPUT_ARM64]]", {{.*}} "--target=arm64-apple-macosx12.0.0"]},
+// CHECK-NEXT: EOF