diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -102,7 +102,7 @@
 
 // Default filename used for profile generation.
 std::string getDefaultProfileGenName() {
-  return DebugInfoCorrelate ? "default_%m.proflite" : "default_%m.profraw";
+  return DebugInfoCorrelate ? "default_%p.proflite" : "default_%m.profraw";
 }
 
 class EmitAssemblyHelper {
diff --git a/compiler-rt/lib/profile/InstrProfilingMerge.c b/compiler-rt/lib/profile/InstrProfilingMerge.c
--- a/compiler-rt/lib/profile/InstrProfilingMerge.c
+++ b/compiler-rt/lib/profile/InstrProfilingMerge.c
@@ -95,8 +95,13 @@
 COMPILER_RT_VISIBILITY
 int __llvm_profile_merge_from_buffer(const char *ProfileData,
                                      uint64_t ProfileSize) {
-  if (__llvm_profile_get_version() & VARIANT_MASK_DBG_CORRELATE)
+  if (__llvm_profile_get_version() & VARIANT_MASK_DBG_CORRELATE) {
+    PROF_ERR(
+        "%s\n",
+        "Debug info correlation does not support profile merging at runtime. "
+        "Instead, merge raw profiles using the llvm-profdata tool.");
     return 1;
+  }
 
   __llvm_profile_data *SrcDataStart, *SrcDataEnd, *SrcData, *DstData;
   __llvm_profile_header *Header = (__llvm_profile_header *)ProfileData;