Index: include/clang/Format/Format.h
===================================================================
--- include/clang/Format/Format.h
+++ include/clang/Format/Format.h
@@ -1718,6 +1718,9 @@
   /// Defines in which cases to put a space before opening parentheses.
   SpaceBeforeParensOptions SpaceBeforeParens;
 
+  /// Defines whether a space should be placed after a logical `!`
+  bool SpaceAfterLogicalNot;
+
   /// If ``false``, spaces will be removed before range-based for loop
   /// colon.
   /// \code
@@ -1726,7 +1729,7 @@
   /// \endcode
   bool SpaceBeforeRangeBasedForLoopColon;
 
-  /// If ``true``, spaces may be inserted into ``()``.
+  /// \brief If ``true``, spaces may be inserted into ``()``.
   /// \code
   ///    true:                                false:
   ///    void f( ) {                    vs.   void f() {
@@ -1918,6 +1921,7 @@
                R.SpaceBeforeCtorInitializerColon &&
            SpaceBeforeInheritanceColon == R.SpaceBeforeInheritanceColon &&
            SpaceBeforeParens == R.SpaceBeforeParens &&
+           SpaceAfterLogicalNot == R.SpaceAfterLogicalNot &&
            SpaceBeforeRangeBasedForLoopColon ==
                R.SpaceBeforeRangeBasedForLoopColon &&
            SpaceInEmptyParentheses == R.SpaceInEmptyParentheses &&
Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -489,6 +489,7 @@
     IO.mapOptional("SpaceBeforeInheritanceColon",
                    Style.SpaceBeforeInheritanceColon);
     IO.mapOptional("SpaceBeforeParens", Style.SpaceBeforeParens);
+    IO.mapOptional("SpaceAfterLogicalNot", Style.SpaceAfterLogicalNot);
     IO.mapOptional("SpaceBeforeRangeBasedForLoopColon",
                    Style.SpaceBeforeRangeBasedForLoopColon);
     IO.mapOptional("SpaceInEmptyParentheses", Style.SpaceInEmptyParentheses);
@@ -726,6 +727,7 @@
   LLVMStyle.ReflowComments = true;
   LLVMStyle.SpacesInParentheses = false;
   LLVMStyle.SpacesInSquareBrackets = false;
+  LLVMStyle.SpaceAfterLogicalNot = false;
   LLVMStyle.SpaceInEmptyParentheses = false;
   LLVMStyle.SpacesInContainerLiterals = true;
   LLVMStyle.SpacesInCStyleCastParentheses = false;
Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -2831,8 +2831,10 @@
       return false;
     return true;
   }
-  if (Left.is(TT_UnaryOperator))
-    return Right.is(TT_BinaryOperator);
+  if (Left.is(TT_UnaryOperator)) {
+    return (Style.SpaceAfterLogicalNot && Left.is(tok::exclaim)) ||
+           Right.is(TT_BinaryOperator);
+  }
 
   // If the next token is a binary operator or a selector name, we have
   // incorrectly classified the parenthesis as a cast. FIXME: Detect correctly.
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -9683,6 +9683,16 @@
   verifyFormat("auto lambda = []() { return 0; };", SomeSpace);
 }
 
+TEST_F(FormatTest, SpaceAfterLogicalNot) {
+  FormatStyle Spaces = getLLVMStyle();
+  Spaces.SpaceAfterLogicalNot = true;
+
+  verifyFormat("bool x = ! y", Spaces);
+  verifyFormat("if (! isFailure())", Spaces);
+  verifyFormat("if (! (a && b))", Spaces);
+  verifyFormat("\"Error!\"", Spaces);
+}
+
 TEST_F(FormatTest, ConfigurableSpacesInParentheses) {
   FormatStyle Spaces = getLLVMStyle();
 
@@ -11475,6 +11485,12 @@
   CHECK_PARSE("SpaceAfterControlStatementKeyword: true", SpaceBeforeParens,
               FormatStyle::SBPO_ControlStatements);
 
+  Style.SpaceAfterLogicalNot = false;
+  CHECK_PARSE("SpaceAfterLogicalNot: true", SpaceAfterLogicalNot,
+              true);
+  CHECK_PARSE("SpaceAfterLogicalNot: false", SpaceAfterLogicalNot,
+              false);
+
   Style.ColumnLimit = 123;
   FormatStyle BaseStyle = getLLVMStyle();
   CHECK_PARSE("BasedOnStyle: LLVM", ColumnLimit, BaseStyle.ColumnLimit);