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
@@ -119,10 +119,12 @@
                                               MlirStringCallback callback,
                                               void *userData);
 
-/// Parse a textual MLIR pass pipeline and add it to the provided OpPassManager.
-
+/// Parse a textual MLIR pass pipeline and assign it to the provided
+/// OpPassManager. If parsing fails an error message is reported using the
+/// provided callback.
 MLIR_CAPI_EXPORTED MlirLogicalResult
-mlirParsePassPipeline(MlirOpPassManager passManager, MlirStringRef pipeline);
+mlirParsePassPipeline(MlirOpPassManager passManager, MlirStringRef pipeline,
+                      MlirStringCallback callback, void *userData);
 
 //===----------------------------------------------------------------------===//
 // External Pass API.
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
@@ -81,10 +81,14 @@
 }
 
 MlirLogicalResult mlirParsePassPipeline(MlirOpPassManager passManager,
-                                        MlirStringRef pipeline) {
-  // TODO: errors are sent to std::errs() at the moment, we should pass in a
-  // stream and redirect to a diagnostic.
-  return wrap(mlir::parsePassPipeline(unwrap(pipeline), *unwrap(passManager)));
+                                        MlirStringRef pipeline,
+                                        MlirStringCallback callback,
+                                        void *userData) {
+  detail::CallbackOstream stream(callback, userData);
+  FailureOr<OpPassManager> pm = parsePassPipeline(unwrap(pipeline), stream);
+  if (succeeded(pm))
+    *unwrap(passManager) = std::move(*pm);
+  return wrap(pm);
 }
 
 //===----------------------------------------------------------------------===//
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
@@ -176,7 +176,8 @@
   MlirLogicalResult status = mlirParsePassPipeline(
       mlirPassManagerGetAsOpPassManager(pm),
       mlirStringRefCreateFromCString(
-          "builtin.module(func.func(print-op-stats{json=false}))"));
+          "builtin.module(func.func(print-op-stats{json=false}))"),
+      printToStderr, NULL);
   // Expect a failure, we haven't registered the print-op-stats pass yet.
   if (mlirLogicalResultIsSuccess(status)) {
     fprintf(
@@ -189,7 +190,8 @@
   status = mlirParsePassPipeline(
       mlirPassManagerGetAsOpPassManager(pm),
       mlirStringRefCreateFromCString(
-          "builtin.module(func.func(print-op-stats{json=false}))"));
+          "builtin.module(func.func(print-op-stats{json=false}))"),
+      printToStderr, NULL);
   // Expect a failure, we haven't registered the print-op-stats pass yet.
   if (mlirLogicalResultIsFailure(status)) {
     fprintf(stderr,
@@ -197,9 +199,7 @@
     exit(EXIT_FAILURE);
   }
 
-  //      CHECK: Round-trip: builtin.module(
-  // CHECK-SAME:   builtin.module(func.func(print-op-stats{json=false}))
-  // CHECK-SAME: )
+  // CHECK: Round-trip: builtin.module(func.func(print-op-stats{json=false}))
   fprintf(stderr, "Round-trip: ");
   mlirPrintPassPipeline(mlirPassManagerGetAsOpPassManager(pm), printToStderr,
                         NULL);
@@ -215,7 +215,7 @@
     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:   func.func(print-op-stats{json=false})
   // CHECK-SAME: )
   fprintf(stderr, "Appended: ");