Index: clang/docs/ClangFormatStyleOptions.rst
===================================================================
--- clang/docs/ClangFormatStyleOptions.rst
+++ clang/docs/ClangFormatStyleOptions.rst
@@ -1952,6 +1952,13 @@
      true:                                  false:
      (int) i;                       vs.     (int)i;
 
+**SpaceAfterLogicalNot** (``bool``)
+  If ``true``, a space is inserted after the logical not operator (``!``).
+  .. code-block:: c++
+
+     true:                                  false:
+     ! someExpression();            vs.     !someExpression();
+
 **SpaceAfterTemplateKeyword** (``bool``)
   If ``true``, a space will be inserted after the 'template' keyword.
 
Index: clang/include/clang/Format/Format.h
===================================================================
--- clang/include/clang/Format/Format.h
+++ clang/include/clang/Format/Format.h
@@ -1628,6 +1628,13 @@
   /// \endcode
   bool SpaceAfterCStyleCast;
 
+  /// If ``true``, a space is inserted after the logical not operator (``!``).
+  /// \code
+  ///    true:                                  false:
+  ///    ! someExpression();            vs.     !someExpression();
+  /// \endcode
+  bool SpaceAfterLogicalNot;
+
   /// If \c true, a space will be inserted after the 'template' keyword.
   /// \code
   ///    true:                                  false:
@@ -1911,6 +1918,7 @@
            PointerAlignment == R.PointerAlignment &&
            RawStringFormats == R.RawStringFormats &&
            SpaceAfterCStyleCast == R.SpaceAfterCStyleCast &&
+           SpaceAfterLogicalNot == R.SpaceAfterLogicalNot &&
            SpaceAfterTemplateKeyword == R.SpaceAfterTemplateKeyword &&
            SpaceBeforeAssignmentOperators == R.SpaceBeforeAssignmentOperators &&
            SpaceBeforeCpp11BracedList == R.SpaceBeforeCpp11BracedList &&
Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -478,6 +478,7 @@
     IO.mapOptional("SortIncludes", Style.SortIncludes);
     IO.mapOptional("SortUsingDeclarations", Style.SortUsingDeclarations);
     IO.mapOptional("SpaceAfterCStyleCast", Style.SpaceAfterCStyleCast);
+    IO.mapOptional("SpaceAfterLogicalNot", Style.SpaceAfterLogicalNot);
     IO.mapOptional("SpaceAfterTemplateKeyword",
                    Style.SpaceAfterTemplateKeyword);
     IO.mapOptional("SpaceBeforeAssignmentOperators",
@@ -730,6 +731,7 @@
   LLVMStyle.SpacesInContainerLiterals = true;
   LLVMStyle.SpacesInCStyleCastParentheses = false;
   LLVMStyle.SpaceAfterCStyleCast = false;
+  LLVMStyle.SpaceAfterLogicalNot = false;
   LLVMStyle.SpaceAfterTemplateKeyword = true;
   LLVMStyle.SpaceBeforeCtorInitializerColon = true;
   LLVMStyle.SpaceBeforeInheritanceColon = true;
Index: clang/lib/Format/TokenAnnotator.cpp
===================================================================
--- clang/lib/Format/TokenAnnotator.cpp
+++ clang/lib/Format/TokenAnnotator.cpp
@@ -2832,7 +2832,8 @@
     return true;
   }
   if (Left.is(TT_UnaryOperator))
-    return Right.is(TT_BinaryOperator);
+    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: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -9719,6 +9719,17 @@
   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);
+  verifyFormat("! ! x", Spaces);
+}
+
 TEST_F(FormatTest, ConfigurableSpacesInParentheses) {
   FormatStyle Spaces = getLLVMStyle();
 
@@ -11511,6 +11522,12 @@
   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);