Index: include/clang/Format/Format.h
===================================================================
--- include/clang/Format/Format.h
+++ include/clang/Format/Format.h
@@ -410,6 +410,9 @@
   /// \brief If \c true, spaces will be inserted after '[' and before ']'.
   bool SpacesInSquareBrackets;
 
+  /// \brief If \c true, a space will be inserted before '[' in array subscripts.
+  bool SpaceBeforeSquareBrackets;
+
   /// \brief Supported language standards.
   enum LanguageStandard {
     /// Use C++03-compatible syntax.
@@ -515,6 +518,7 @@
            SpacesInCStyleCastParentheses == R.SpacesInCStyleCastParentheses &&
            SpacesInParentheses == R.SpacesInParentheses &&
            SpacesInSquareBrackets == R.SpacesInSquareBrackets &&
+           SpaceBeforeSquareBrackets == R.SpaceBeforeSquareBrackets &&
            Standard == R.Standard &&
            TabWidth == R.TabWidth &&
            UseTab == R.UseTab;
Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -279,6 +279,7 @@
                    Style.SpacesInCStyleCastParentheses);
     IO.mapOptional("SpacesInParentheses", Style.SpacesInParentheses);
     IO.mapOptional("SpacesInSquareBrackets", Style.SpacesInSquareBrackets);
+    IO.mapOptional("SpaceBeforeSquareBrackets", Style.SpaceBeforeSquareBrackets);
     IO.mapOptional("Standard", Style.Standard);
     IO.mapOptional("TabWidth", Style.TabWidth);
     IO.mapOptional("UseTab", Style.UseTab);
@@ -391,6 +392,7 @@
   LLVMStyle.UseTab = FormatStyle::UT_Never;
   LLVMStyle.SpacesInParentheses = false;
   LLVMStyle.SpacesInSquareBrackets = false;
+  LLVMStyle.SpaceBeforeSquareBrackets = false;
   LLVMStyle.SpaceInEmptyParentheses = false;
   LLVMStyle.SpacesInContainerLiterals = true;
   LLVMStyle.SpacesInCStyleCastParentheses = false;
Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -1882,7 +1882,9 @@
              Right.MatchingParen->is(TT_ArraySubscriptLSquare)));
   if (Right.is(tok::l_square) &&
       !Right.isOneOf(TT_ObjCMethodExpr, TT_LambdaLSquare) &&
-      !Left.isOneOf(tok::numeric_constant, TT_DictLiteral))
+      !Left.isOneOf(tok::numeric_constant, TT_DictLiteral) &&
+      !(!Left.is(tok::r_square) && Style.SpaceBeforeSquareBrackets &&
+        Right.is(TT_ArraySubscriptLSquare)))
     return false;
   if (Left.is(tok::colon))
     return !Left.is(TT_ObjCMethodExpr);
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -8358,6 +8358,43 @@
   verifyFormat("X A::operator++ (T);", Space);
 }
 
+TEST_F(FormatTest, ConfigurableSpaceBeforeSquareBrackets) {
+  FormatStyle NoSpace = getLLVMStyle();
+  NoSpace.SpaceBeforeSquareBrackets = false;
+  
+  verifyFormat("int a[5];", NoSpace);
+  verifyFormat("a[3] += 42;", NoSpace);
+
+  verifyFormat("int a[1];", NoSpace);
+  verifyFormat("int 1 [a];", NoSpace);
+  verifyFormat("int a[1][2];", NoSpace);
+  verifyFormat("a[7] = 5;", NoSpace);
+  verifyFormat("int a = (f())[23];", NoSpace);
+  verifyFormat("f([] {})", NoSpace);
+
+  FormatStyle Space = getLLVMStyle();
+  Space.SpaceBeforeSquareBrackets = true;
+  verifyFormat("int c = []() -> int { return 2; }();\n", Space);
+  verifyFormat("return [i, args...] {};", Space);
+
+  verifyFormat("int a [5];", Space);
+  verifyFormat("a [3] += 42;", Space);
+  verifyFormat("constexpr char hello []{\"hello\"};", Space);
+  verifyFormat("double &operator[](int i) { return 0; }\n"
+                "int i;",
+                Space);
+  verifyFormat("std::unique_ptr<int []> foo() {}", Space);
+  verifyFormat("int i = a [a][a]->f();", Space);
+  verifyFormat("int i = (*b) [a]->f();", Space);
+
+  verifyFormat("int a [1];", Space);
+  verifyFormat("int 1 [a];", Space);
+  verifyFormat("int a [1][2];", Space);
+  verifyFormat("a [7] = 5;", Space);
+  verifyFormat("int a = (f()) [23];", Space);
+  verifyFormat("f([] {})", Space);
+}
+
 TEST_F(FormatTest, ConfigurableSpacesInParentheses) {
   FormatStyle Spaces = getLLVMStyle();
 
@@ -9303,6 +9340,7 @@
   CHECK_PARSE_BOOL(SpacesInCStyleCastParentheses);
   CHECK_PARSE_BOOL(SpaceAfterCStyleCast);
   CHECK_PARSE_BOOL(SpaceBeforeAssignmentOperators);
+  CHECK_PARSE_BOOL(SpaceBeforeSquareBrackets);
 }
 
 #undef CHECK_PARSE_BOOL