diff --git a/llvm/lib/ProfileData/SampleProfWriter.cpp b/llvm/lib/ProfileData/SampleProfWriter.cpp
--- a/llvm/lib/ProfileData/SampleProfWriter.cpp
+++ b/llvm/lib/ProfileData/SampleProfWriter.cpp
@@ -125,6 +125,9 @@
   LLVM_DEBUG(dbgs() << "Profile originally has " << OriginalFunctionCount
                     << " functions, reduced to " << ProfileMap.size() << " in "
                     << IterationCount << " iterations\n");
+  // Silence warning on Release build.
+  (void)OriginalFunctionCount;
+  (void)IterationCount;
   return sampleprof_error::success;
 }
 
diff --git a/llvm/unittests/tools/llvm-profdata/OutputSizeLimitTest.cpp b/llvm/unittests/tools/llvm-profdata/OutputSizeLimitTest.cpp
--- a/llvm/unittests/tools/llvm-profdata/OutputSizeLimitTest.cpp
+++ b/llvm/unittests/tools/llvm-profdata/OutputSizeLimitTest.cpp
@@ -33,15 +33,17 @@
 _Z3fooi:7711:610
  1: 610)";
 
+static void CheckAssertFalse(std::error_code t) {
+  ASSERT_FALSE(t) << t.message().c_str();
+}
+
 static SampleProfileMap ReadInput(StringRef Input) {
   LLVMContext Context;
   auto InputBuffer = MemoryBuffer::getMemBufferCopy(Input);
   auto ReaderOrErr = SampleProfileReader::create(InputBuffer, Context);
-  if (std::error_code EC = ReaderOrErr.getError())
-    report_fatal_error(EC.message().c_str());
+  CheckAssertFalse(ReaderOrErr.getError());
   auto Reader = std::move(ReaderOrErr.get());
-  if (std::error_code EC = Reader->read())
-    report_fatal_error(EC.message().c_str());
+  CheckAssertFalse(Reader->read());
   return Reader->getProfiles();
 }
 
@@ -51,22 +53,26 @@
       new raw_svector_ostream(OutputBuffer));
   auto WriterOrErr = SampleProfileWriter::create(
       BufferStream, llvm::sampleprof::SPF_Ext_Binary);
-  if (std::error_code EC = WriterOrErr.getError())
-    report_fatal_error(EC.message().c_str());
+  CheckAssertFalse(WriterOrErr.getError());
   return std::move(WriterOrErr.get());
 }
 
-// Only returns the actual size of the written profile.
+// Returns the actual size of the written profile.
 static size_t WriteProfile(StringRef Input, size_t SizeLimit) {
   SampleProfileMap Profiles = ReadInput(Input);
   SmallVector<char> OutputBuffer;
   auto Writer = CreateWriter(OutputBuffer);
-  if (std::error_code EC = Writer->writeWithSizeLimit(Profiles, SizeLimit))
-    report_fatal_error(EC.message().c_str());
+  std::error_code EC = Writer->writeWithSizeLimit(Profiles, SizeLimit);
+  // too_large means no sample could be written because SizeLimit is too small.
+  // Otherwise any other error code indicates unexpected failure.
+  if (EC == sampleprof_error::too_large)
+    return 0;
+  else
+    CheckAssertFalse(EC);
   return OutputBuffer.size();
 }
 
 TEST(TestOutputSizeLimit, TestOutputSizeLimit1) {
-  for (size_t OutputSizeLimit : {489, 488, 474})
-    ASSERT_LE(WriteProfile(Input1, OutputSizeLimit), OutputSizeLimit);
+  for (size_t OutputSizeLimit : {489, 488, 474, 400})
+    EXPECT_LE(WriteProfile(Input1, OutputSizeLimit), OutputSizeLimit);
 }