diff --git a/llvm/include/llvm-c/BitReader.h b/llvm/include/llvm-c/BitReader.h
--- a/llvm/include/llvm-c/BitReader.h
+++ b/llvm/include/llvm-c/BitReader.h
@@ -61,8 +61,13 @@
                                        LLVMMemoryBufferRef MemBuf,
                                        LLVMModuleRef *OutM, char **OutMessage);
 
-/** Reads a module from the specified path, returning via the OutMP parameter a
- * module provider which performs lazy deserialization. Returns 0 on success. */
+/** Reads a module from the given memory buffer, returning via the OutMP
+ * parameter a  * module provider which performs lazy deserialization.
+ *
+ * Returns 0 on success.
+ *
+ * Takes ownership of \p MemBuf if (and only if) the module was read
+ * successfully. */
 LLVMBool LLVMGetBitcodeModuleInContext2(LLVMContextRef ContextRef,
                                         LLVMMemoryBufferRef MemBuf,
                                         LLVMModuleRef *OutM);
diff --git a/llvm/tools/llvm-c-test/diagnostic.c b/llvm/tools/llvm-c-test/diagnostic.c
--- a/llvm/tools/llvm-c-test/diagnostic.c
+++ b/llvm/tools/llvm-c-test/diagnostic.c
@@ -70,13 +70,8 @@
 
   LLVMModuleRef M;
   int Ret = LLVMGetBitcodeModule2(MB, &M);
-  if (Ret) {
-    // We do not return if the bitcode was invalid, as we want to test whether
-    // the diagnostic handler was executed.
-    fprintf(stderr, "Error parsing bitcode: %s\n", msg);
-  }
-
-  LLVMDisposeMemoryBuffer(MB);
+  if (Ret)
+    LLVMDisposeMemoryBuffer(MB);
 
   if (handlerCalled) {
     fprintf(stderr, "Diagnostic handler was called while loading module\n");