diff --git a/src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs b/src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs
index 726df7260335e..8e38f5de7ff54 100644
--- a/src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs
+++ b/src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs
@@ -12497,6 +12497,11 @@ public void TestCategoryBasedBulkAnalyzerDiagnosticConfiguration(DiagnosticSever
 dotnet_analyzer_diagnostic.category-{category}.severity = error";
             TestBulkAnalyzerConfigurationCore(analyzer, analyzerConfigText, errorlog, expectedDiagnosticSeverity: ReportDiagnostic.Warn);
 
+            // Verify category based configuration to warning + /warnaserror reports errors.
+            analyzerConfigText = $@"
+[*.cs]
+dotnet_analyzer_diagnostic.category-{category}.severity = warning";
+            TestBulkAnalyzerConfigurationCore(analyzer, analyzerConfigText, errorlog, warnAsError: true, expectedDiagnosticSeverity: ReportDiagnostic.Error);
 
             // Verify disabled by default analyzer is not enabled by category based configuration.
             analyzer = new NamedTypeAnalyzerWithConfigurableEnabledByDefault(isEnabledByDefault: false, defaultSeverity);
@@ -12577,6 +12582,12 @@ public void TestBulkAnalyzerDiagnosticConfiguration(DiagnosticSeverity defaultSe
 dotnet_analyzer_diagnostic.severity = error";
             TestBulkAnalyzerConfigurationCore(analyzer, analyzerConfigText, errorlog, expectedDiagnosticSeverity: ReportDiagnostic.Warn);
 
+            // Verify bulk configuration to warning + /warnaserror reports errors.
+            analyzerConfigText = $@"
+[*.cs]
+dotnet_analyzer_diagnostic.severity = warning";
+            TestBulkAnalyzerConfigurationCore(analyzer, analyzerConfigText, errorlog, warnAsError: true, expectedDiagnosticSeverity: ReportDiagnostic.Error);
+
             // Verify disabled by default analyzer is not enabled by bulk configuration.
             analyzer = new NamedTypeAnalyzerWithConfigurableEnabledByDefault(isEnabledByDefault: false, defaultSeverity);
             analyzerConfigText = $@"
@@ -12654,7 +12665,8 @@ private void TestBulkAnalyzerConfigurationCore(
             bool errorlog,
             ReportDiagnostic expectedDiagnosticSeverity,
             string rulesetText = null,
-            bool noWarn = false)
+            bool noWarn = false,
+            bool warnAsError = false)
         {
             var diagnosticId = analyzer.Descriptor.Id;
             var dir = Temp.CreateDirectory();
@@ -12672,6 +12684,11 @@ private void TestBulkAnalyzerConfigurationCore(
                 arguments = arguments.Append($"/nowarn:{diagnosticId}");
             }
 
+            if (warnAsError)
+            {
+                arguments = arguments.Append($"/warnaserror");
+            }
+
             if (errorlog)
             {
                 arguments = arguments.Append($"/errorlog:errorlog");
diff --git a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerOptionsExtensions.cs b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerOptionsExtensions.cs
index c0f2fda23b531..1ef1e3684300a 100644
--- a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerOptionsExtensions.cs
+++ b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerOptionsExtensions.cs
@@ -66,6 +66,10 @@ public static bool TryGetSeverityFromBulkConfiguration(
             if (analyzerConfigOptions.TryGetValue(categoryBasedKey, out var value) &&
                 AnalyzerConfigSet.TryParseSeverity(value, out severity))
             {
+                // '/warnaserror' should bump Warning bulk configuration to Error.
+                if (severity == ReportDiagnostic.Warn && compilation.Options.GeneralDiagnosticOption == ReportDiagnostic.Error)
+                    severity = ReportDiagnostic.Error;
+
                 return true;
             }
 
@@ -74,6 +78,10 @@ public static bool TryGetSeverityFromBulkConfiguration(
             if (analyzerConfigOptions.TryGetValue(DotnetAnalyzerDiagnosticSeverityKey, out value) &&
                 AnalyzerConfigSet.TryParseSeverity(value, out severity))
             {
+                // '/warnaserror' should bump Warning bulk configuration to Error.
+                if (severity == ReportDiagnostic.Warn && compilation.Options.GeneralDiagnosticOption == ReportDiagnostic.Error)
+                    severity = ReportDiagnostic.Error;
+
                 return true;
             }