diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2999,6 +2999,10 @@
 def warn_objc_string_literal_comparison : Warning<
   "direct comparison of a string literal has undefined behavior">,
   InGroup<ObjCStringComparison>;
+def warn_concatenated_literal_array_init : Warning<
+  "concatenated literal in a string array initialization - "
+  "possibly missing a comma">,
+  InGroup<DiagGroup<"string-concatenation">>;
 def warn_concatenated_nsarray_literal : Warning<
   "concatenated NSString literal for an NSArray expression - "
   "possibly missing a comma">,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6907,6 +6907,11 @@
         << DIE->getSourceRange();
       Diag(InitArgList[I]->getBeginLoc(), diag::note_designated_init_mixed)
         << InitArgList[I]->getSourceRange();
+    } else if (StringLiteral *SL = dyn_cast<StringLiteral>(InitArgList[I])) {
+      unsigned numConcat = SL->getNumConcatenated();
+      // Diagnose missing comma in string array initialization.
+      if (numConcat > 1)
+        Diag(SL->getBeginLoc(), diag::warn_concatenated_literal_array_init);
     }
   }
 
diff --git a/clang/test/Sema/string-concat.c b/clang/test/Sema/string-concat.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/string-concat.c
@@ -0,0 +1,41 @@
+
+// RUN: %clang_cc1 -x c -fsyntax-only -verify %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify %s
+
+const char *test1[] = {
+    "basic_filebuf",
+    "basic_ios",
+    "future",
+    "optional",
+    "packaged_task" // expected-warning{{concatenated literal in a string array initialization - possibly missing a comma}}
+    "promise",
+    "shared_future",
+    "shared_lock",
+    "shared_ptr",
+    "thread",
+    "unique_ptr",
+    "unique_lock",
+    "weak_ptr",
+};
+
+const char *test2[] = {"basic_filebuf",
+                       "basic_ios" // expected-warning{{concatenated literal in a string array initialization - possibly missing a comma}}
+                       "future"
+                       "optional",
+                       "packaged_task"};
+
+const char *test3[] = {"basic_filebuf", "basic_ios",
+                       "future" "optional", // expected-warning{{concatenated literal in a string array initialization - possibly missing a comma}}
+                       "packaged_task", "promise"};
+
+const char *test4[] = {"basic_filebuf", "basic_ios" // expected-warning{{concatenated literal in a string array initialization - possibly missing a comma}}
+                       "future", "optional",
+                       "packaged_task", "promise"};
+
+#define BASIC_IOS "basic_ios"
+#define FUTURE "future"
+const char *test5[] = {"basic_filebuf", BASIC_IOS // expected-warning{{concatenated literal in a string array initialization - possibly missing a comma}}
+                        FUTURE, "optional",
+                       "packaged_task", "promise"};
+
+const char *test6[] = {"basic_filebuf", "future" "optional", "packaged_task"}; // expected-warning{{concatenated literal in a string array initialization - possibly missing a comma}}