Index: clang/lib/Driver/SanitizerArgs.cpp
===================================================================
--- clang/lib/Driver/SanitizerArgs.cpp
+++ clang/lib/Driver/SanitizerArgs.cpp
@@ -117,6 +117,19 @@
 /// Sanitizers set.
 static std::string toString(const clang::SanitizerSet &Sanitizers);
 
+static void validateSpecialCaseListFormat(const Driver &D,
+                                          std::vector<std::string> &SCLFiles,
+                                          unsigned MalformedSCLErrorDiagID) {
+  if (SCLFiles.empty())
+    return;
+
+  std::string BLError;
+  std::unique_ptr<llvm::SpecialCaseList> SCL(
+      llvm::SpecialCaseList::create(SCLFiles, D.getVFS(), BLError));
+  if (!SCL.get())
+    D.Diag(MalformedSCLErrorDiagID) << BLError;
+}
+
 static void addDefaultBlacklists(const Driver &D, SanitizerMask Kinds,
                                  std::vector<std::string> &BlacklistFiles) {
   struct Blacklist {
@@ -147,6 +160,8 @@
       // should fail.
       D.Diag(clang::diag::err_drv_no_such_file) << Path;
   }
+  validateSpecialCaseListFormat(
+      D, BlacklistFiles, clang::diag::err_drv_malformed_sanitizer_blacklist);
 }
 
 /// Parse -f(no-)?sanitize-(coverage-)?(white|black)list argument's values,
@@ -173,14 +188,7 @@
       SCLFiles.clear();
     }
   }
-  // Validate special case list format.
-  {
-    std::string BLError;
-    std::unique_ptr<llvm::SpecialCaseList> SCL(
-        llvm::SpecialCaseList::create(SCLFiles, D.getVFS(), BLError));
-    if (!SCL.get())
-      D.Diag(MalformedSCLErrorDiagID) << BLError;
-  }
+  validateSpecialCaseListFormat(D, SCLFiles, MalformedSCLErrorDiagID);
 }
 
 /// Sets group bits for every group that has at least one representative already
@@ -566,16 +574,13 @@
   RecoverableKinds &= ~TrappingKinds;
 
   // Setup blacklist files.
-  // Add default blacklist from resource directory.
-  addDefaultBlacklists(D, Kinds, SystemBlacklistFiles);
+  // Add default blacklist from resource directory for activated sanitizers, and
+  // validate special case lists format.
+  if (!Args.hasArgNoClaim(options::OPT_fno_sanitize_blacklist))
+    addDefaultBlacklists(D, Kinds, SystemBlacklistFiles);
 
   // Parse -f(no-)?sanitize-blacklist options.
   // This also validates special case lists format.
-  // Here, OptSpecifier() acts as a never-matching command-line argument.
-  // So, there is no way to append to system blacklist but it can be cleared.
-  parseSpecialCaseListArg(D, Args, SystemBlacklistFiles, OptSpecifier(),
-                          options::OPT_fno_sanitize_blacklist,
-                          clang::diag::err_drv_malformed_sanitizer_blacklist);
   parseSpecialCaseListArg(D, Args, UserBlacklistFiles,
                           options::OPT_fsanitize_blacklist,
                           options::OPT_fno_sanitize_blacklist,
Index: clang/test/Driver/fsanitize-blacklist.c
===================================================================
--- clang/test/Driver/fsanitize-blacklist.c
+++ clang/test/Driver/fsanitize-blacklist.c
@@ -59,8 +59,16 @@
 // CHECK-ONLY-FIRST-DISABLED: -fsanitize-blacklist={{.*}}.second
 // CHECK-ONLY_FIRST-DISABLED-NOT: good
 
+// -fno-sanitize-blacklist disables the system blacklists.
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=address -fno-sanitize-blacklist %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-DISABLED-SYSTEM --check-prefix=DELIMITERS
+// CHECK-DISABLED-SYSTEM-NOT: -fsanitize-system-blacklist
+
 // If cfi_blacklist.txt cannot be found in the resource dir, driver should fail.
-// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi -resource-dir=/dev/null %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-MISSING-CFI-BLACKLIST
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi -flto -fvisibility=default -resource-dir=/dev/null %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-MISSING-CFI-BLACKLIST
 // CHECK-MISSING-CFI-BLACKLIST: error: no such file or directory: '{{.*}}cfi_blacklist.txt'
 
+// -fno-sanitize-blacklist disables checking for cfi_blacklist.txt in the resource dir.
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi -flto -fvisibility=default -fno-sanitize-blacklist -resource-dir=/dev/null %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-MISSING-CFI-NO-BLACKLIST
+// CHECK-MISSING-CFI-NO-BLACKLIST-NOT: error: no such file or directory: '{{.*}}cfi_blacklist.txt'
+
 // DELIMITERS: {{^ *"}}