diff --git a/mlir/include/mlir-c/Pass.h b/mlir/include/mlir-c/Pass.h
--- a/mlir/include/mlir-c/Pass.h
+++ b/mlir/include/mlir-c/Pass.h
@@ -105,6 +105,13 @@
 MLIR_CAPI_EXPORTED void
 mlirOpPassManagerAddOwnedPass(MlirOpPassManager passManager, MlirPass pass);
 
+/// Parse a sequence of textual MLIR pass pipeline elements and add them to the
+/// provided OpPassManager. If parsing fails an error message is reported using
+/// the provided callback.
+MLIR_CAPI_EXPORTED MlirLogicalResult mlirOpPassManagerAddPipeline(
+    MlirOpPassManager passManager, MlirStringRef pipelineElements,
+    MlirStringCallback callback, void *userData);
+
 /// Print a textual MLIR pass pipeline by sending chunks of the string
 /// representation and forwarding `userData to `callback`. Note that the
 /// callback may be called several times with consecutive chunks of the string.
diff --git a/mlir/lib/Bindings/Python/Pass.cpp b/mlir/lib/Bindings/Python/Pass.cpp
--- a/mlir/lib/Bindings/Python/Pass.cpp
+++ b/mlir/lib/Bindings/Python/Pass.cpp
@@ -82,15 +82,15 @@
           py::arg("enable"), "Enable / disable verify-each.")
       .def_static(
           "parse",
-          [](const std::string pipeline, DefaultingPyMlirContext context) {
+          [](const std::string &pipeline, DefaultingPyMlirContext context) {
             MlirPassManager passManager = mlirPassManagerCreate(context->get());
-            MlirLogicalResult status = mlirParsePassPipeline(
+            PyPrintAccumulator errorMsg;
+            MlirLogicalResult status = mlirOpPassManagerAddPipeline(
                 mlirPassManagerGetAsOpPassManager(passManager),
-                mlirStringRefCreate(pipeline.data(), pipeline.size()));
+                mlirStringRefCreate(pipeline.data(), pipeline.size()),
+                errorMsg.getCallback(), errorMsg.getUserData());
             if (mlirLogicalResultIsFailure(status))
-              throw SetPyError(PyExc_ValueError,
-                               llvm::Twine("invalid pass pipeline '") +
-                                   pipeline + "'.");
+              throw SetPyError(PyExc_ValueError, std::string(errorMsg.join()));
             return new PyPassManager(passManager);
           },
           py::arg("pipeline"), py::arg("context") = py::none(),
diff --git a/mlir/lib/CAPI/IR/Pass.cpp b/mlir/lib/CAPI/IR/Pass.cpp
--- a/mlir/lib/CAPI/IR/Pass.cpp
+++ b/mlir/lib/CAPI/IR/Pass.cpp
@@ -65,6 +65,15 @@
   unwrap(passManager)->addPass(std::unique_ptr<Pass>(unwrap(pass)));
 }
 
+MlirLogicalResult mlirOpPassManagerAddPipeline(MlirOpPassManager passManager,
+                                               MlirStringRef pipelineElements,
+                                               MlirStringCallback callback,
+                                               void *userData) {
+  detail::CallbackOstream stream(callback, userData);
+  return wrap(parsePassPipeline(unwrap(pipelineElements), *unwrap(passManager),
+                                stream));
+}
+
 void mlirPrintPassPipeline(MlirOpPassManager passManager,
                            MlirStringCallback callback, void *userData) {
   detail::CallbackOstream stream(callback, userData);
diff --git a/mlir/test/CAPI/pass.c b/mlir/test/CAPI/pass.c
--- a/mlir/test/CAPI/pass.c
+++ b/mlir/test/CAPI/pass.c
@@ -176,8 +176,7 @@
   MlirLogicalResult status = mlirParsePassPipeline(
       mlirPassManagerGetAsOpPassManager(pm),
       mlirStringRefCreateFromCString(
-          "builtin.module(func.func(print-op-stats{json=false}),"
-          " func.func(print-op-stats{json=false}))"));
+          "builtin.module(func.func(print-op-stats{json=false}))"));
   // Expect a failure, we haven't registered the print-op-stats pass yet.
   if (mlirLogicalResultIsSuccess(status)) {
     fprintf(
@@ -190,8 +189,7 @@
   status = mlirParsePassPipeline(
       mlirPassManagerGetAsOpPassManager(pm),
       mlirStringRefCreateFromCString(
-          "builtin.module(func.func(print-op-stats{json=false}),"
-          " func.func(print-op-stats{json=false}))"));
+          "builtin.module(func.func(print-op-stats{json=false}))"));
   // Expect a failure, we haven't registered the print-op-stats pass yet.
   if (mlirLogicalResultIsFailure(status)) {
     fprintf(stderr,
@@ -199,14 +197,32 @@
     exit(EXIT_FAILURE);
   }
 
-  //      CHECK: Round-trip: builtin.module(builtin.module(
-  // CHECK-SAME:   func.func(print-op-stats{json=false}),
-  // CHECK-SAME:   func.func(print-op-stats{json=false})
-  // CHECK-SAME: ))
+  //      CHECK: Round-trip: builtin.module(
+  // CHECK-SAME:   builtin.module(func.func(print-op-stats{json=false}))
+  // CHECK-SAME: )
   fprintf(stderr, "Round-trip: ");
   mlirPrintPassPipeline(mlirPassManagerGetAsOpPassManager(pm), printToStderr,
                         NULL);
   fprintf(stderr, "\n");
+
+  // Try appending a pass:
+  status = mlirOpPassManagerAddPipeline(
+      mlirPassManagerGetAsOpPassManager(pm),
+      mlirStringRefCreateFromCString("func.func(print-op-stats{json=false})"),
+      printToStderr, NULL);
+  if (mlirLogicalResultIsFailure(status)) {
+    fprintf(stderr, "Unexpected failure appending pipeline\n");
+    exit(EXIT_FAILURE);
+  }
+  //      CHECK: Appended: builtin.module(
+  // CHECK-SAME:   builtin.module(func.func(print-op-stats{json=false})),
+  // CHECK-SAME:   func.func(print-op-stats{json=false})
+  // CHECK-SAME: )
+  fprintf(stderr, "Appended: ");
+  mlirPrintPassPipeline(mlirPassManagerGetAsOpPassManager(pm), printToStderr,
+                        NULL);
+  fprintf(stderr, "\n");
+
   mlirPassManagerDestroy(pm);
   mlirContextDestroy(ctx);
 }
diff --git a/mlir/test/python/pass_manager.py b/mlir/test/python/pass_manager.py
--- a/mlir/test/python/pass_manager.py
+++ b/mlir/test/python/pass_manager.py
@@ -36,10 +36,8 @@
     # An unregistered pass should not parse.
     try:
       pm = PassManager.parse("builtin.module(func.func(not-existing-pass{json=false}))")
-      # TODO: this error should be propagate to Python but the C API does not help right now.
-      # CHECK: error: 'not-existing-pass' does not refer to a registered pass or pass pipeline
     except ValueError as e:
-      # CHECK: ValueError exception: invalid pass pipeline 'builtin.module(func.func(not-existing-pass{json=false}))'.
+      # CHECK: ValueError exception: {{.+}} 'not-existing-pass' does not refer to a registered pass
       log("ValueError exception:", e)
     else:
       log("Exception not produced")
@@ -57,7 +55,10 @@
     try:
       pm = PassManager.parse("unknown-pass")
     except ValueError as e:
-      # CHECK: ValueError exception: invalid pass pipeline 'unknown-pass'.
+      #      CHECK: ValueError exception: MLIR Textual PassPipeline Parser:1:1: error:
+      # CHECK-SAME: 'unknown-pass' does not refer to a registered pass or pass pipeline
+      #      CHECK: unknown-pass
+      #      CHECK: ^
       log("ValueError exception:", e)
     else:
       log("Exception not produced")
@@ -71,8 +72,7 @@
     try:
       pm = PassManager.parse("func.func(normalize-memrefs)")
     except ValueError as e:
-      # CHECK: Can't add pass 'NormalizeMemRefs' restricted to 'builtin.module' on a PassManager intended to run on 'func.func', did you intend to nest?
-      # CHECK: ValueError exception: invalid pass pipeline 'func.func(normalize-memrefs)'.
+      # CHECK: ValueError exception: Can't add pass 'NormalizeMemRefs' restricted to 'builtin.module' on a PassManager intended to run on 'func.func', did you intend to nest?
       log("ValueError exception:", e)
     else:
       log("Exception not produced")