Index: include/clang/Format/Format.h
===================================================================
--- include/clang/Format/Format.h
+++ include/clang/Format/Format.h
@@ -311,6 +311,9 @@
   /// template argument lists
   bool SpacesInAngles;
 
+  /// \brief If \c true, spaces will be inserted after '[' and before ']'.
+  bool SpacesInSquareBrackets;
+
   /// \brief If \c true, spaces may be inserted into '()'.
   bool SpaceInEmptyParentheses;
 
@@ -414,6 +417,7 @@
            Cpp11BracedListStyle == R.Cpp11BracedListStyle &&
            Standard == R.Standard && TabWidth == R.TabWidth &&
            UseTab == R.UseTab && SpacesInParentheses == R.SpacesInParentheses &&
+           SpacesInSquareBrackets == R.SpacesInSquareBrackets &&
            SpacesInAngles == R.SpacesInAngles &&
            SpaceInEmptyParentheses == R.SpaceInEmptyParentheses &&
            SpacesInContainerLiterals == R.SpacesInContainerLiterals &&
Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -223,6 +223,7 @@
     IO.mapOptional("UseTab", Style.UseTab);
     IO.mapOptional("BreakBeforeBraces", Style.BreakBeforeBraces);
     IO.mapOptional("SpacesInParentheses", Style.SpacesInParentheses);
+    IO.mapOptional("SpacesInSquareBrackets", Style.SpacesInSquareBrackets);
     IO.mapOptional("SpacesInAngles", Style.SpacesInAngles);
     IO.mapOptional("SpaceInEmptyParentheses", Style.SpaceInEmptyParentheses);
     IO.mapOptional("SpacesInCStyleCastParentheses",
@@ -346,6 +347,7 @@
   LLVMStyle.Standard = FormatStyle::LS_Cpp11;
   LLVMStyle.UseTab = FormatStyle::UT_Never;
   LLVMStyle.SpacesInParentheses = false;
+  LLVMStyle.SpacesInSquareBrackets = false;
   LLVMStyle.SpaceInEmptyParentheses = false;
   LLVMStyle.SpacesInContainerLiterals = true;
   LLVMStyle.SpacesInCStyleCastParentheses = false;
Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -1549,11 +1549,16 @@
   if (Right.is(tok::star) && Left.is(tok::l_paren))
     return false;
   if (Left.is(tok::l_square))
-    return Left.Type == TT_ArrayInitializerLSquare &&
-           Style.SpacesInContainerLiterals && Right.isNot(tok::r_square);
+    return (Left.Type == TT_ArrayInitializerLSquare &&
+            Style.SpacesInContainerLiterals && Right.isNot(tok::r_square)) ||
+           (Left.Type == TT_ArraySubscriptLSquare &&
+            Style.SpacesInSquareBrackets && Right.isNot(tok::r_square));
   if (Right.is(tok::r_square))
-    return Right.MatchingParen && Style.SpacesInContainerLiterals &&
-           Right.MatchingParen->Type == TT_ArrayInitializerLSquare;
+    return Right.MatchingParen &&
+           ((Style.SpacesInContainerLiterals &&
+             Right.MatchingParen->Type == TT_ArrayInitializerLSquare) ||
+            (Style.SpacesInSquareBrackets &&
+             Right.MatchingParen->Type == TT_ArraySubscriptLSquare));
   if (Right.is(tok::l_square) && Right.Type != TT_ObjCMethodExpr &&
       Right.Type != TT_LambdaLSquare && Left.isNot(tok::numeric_constant) &&
       Left.Type != TT_DictLiteral)
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -7704,6 +7704,28 @@
                "}", Spaces);
 }
 
+TEST_F(FormatTest, ConfigurableSpacesInSquareBrackets) {
+  verifyFormat("int a[5];");
+  verifyFormat("a[3] += 42;");
+
+  FormatStyle Spaces = getLLVMStyle();
+  Spaces.SpacesInSquareBrackets = true;
+  // Lambdas unchanged.
+  verifyFormat("int c = []() -> int { return 2; }();\n", Spaces);
+  verifyFormat("return [i, args...] {};", Spaces);
+
+  // Not lambdas.
+  verifyFormat("int a[ 5 ];", Spaces);
+  verifyFormat("a[ 3 ] += 42;", Spaces);
+  verifyFormat("constexpr char hello[]{\"hello\"};", Spaces);
+  verifyFormat("double &operator[](int i) { return 0; }\n"
+               "int i;",
+               Spaces);
+  verifyFormat("std::unique_ptr<int[]> foo() {}", Spaces);
+  verifyFormat("int i = a[ a ][ a ]->f();", Spaces);
+  verifyFormat("int i = (*b)[ a ]->f();", Spaces);
+}
+
 TEST_F(FormatTest, ConfigurableSpaceBeforeAssignmentOperators) {
   verifyFormat("int a = 5;");
   verifyFormat("a += 42;");
@@ -8260,6 +8282,7 @@
   CHECK_PARSE_BOOL(ObjCSpaceBeforeProtocolList);
   CHECK_PARSE_BOOL(Cpp11BracedListStyle);
   CHECK_PARSE_BOOL(SpacesInParentheses);
+  CHECK_PARSE_BOOL(SpacesInSquareBrackets);
   CHECK_PARSE_BOOL(SpacesInAngles);
   CHECK_PARSE_BOOL(SpaceInEmptyParentheses);
   CHECK_PARSE_BOOL(SpacesInContainerLiterals);