diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.td
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.td
@@ -42,7 +42,7 @@
 
   let parameters = (ins "Type":$elementType, "unsigned":$numElements);
   let assemblyFormat = [{
-    `<` $numElements `x` ` ` custom<PrettyLLVMType>($elementType) `>`
+    `<` $numElements `x` custom<PrettyLLVMType>($elementType) `>`
   }];
 
   let genVerifyDecl = 1;
@@ -182,7 +182,7 @@
 
   let parameters = (ins "Type":$elementType, "unsigned":$numElements);
   let assemblyFormat = [{
-    `<` $numElements `x` ` ` custom<PrettyLLVMType>($elementType) `>`
+    `<` $numElements `x` custom<PrettyLLVMType>($elementType) `>`
   }];
 
   let genVerifyDecl = 1;
diff --git a/mlir/test/lib/Dialect/Test/TestAttrDefs.td b/mlir/test/lib/Dialect/Test/TestAttrDefs.td
--- a/mlir/test/lib/Dialect/Test/TestAttrDefs.td
+++ b/mlir/test/lib/Dialect/Test/TestAttrDefs.td
@@ -312,7 +312,7 @@
 def TestCustomAnchor : Test_Attr<"TestCustomAnchor"> {
   let parameters = (ins "int":$a, OptionalParameter<"mlir::Optional<int>">:$b);
   let mnemonic = "custom_anchor";
-  let assemblyFormat = "`<` $a (`>`) : (`,` ` ` custom<TrueFalse>($b)^ `>`)?";
+  let assemblyFormat = "`<` $a (`>`) : (`,` custom<TrueFalse>($b)^ `>`)?";
 }
 
 def Test_IteratorTypeEnum
diff --git a/mlir/test/lib/Dialect/Test/TestDialect.cpp b/mlir/test/lib/Dialect/Test/TestDialect.cpp
--- a/mlir/test/lib/Dialect/Test/TestDialect.cpp
+++ b/mlir/test/lib/Dialect/Test/TestDialect.cpp
@@ -680,7 +680,10 @@
   }
   return success();
 }
-
+static ParseResult parseCustomDirectiveSpacing(OpAsmParser &parser,
+                                               mlir::StringAttr &attr) {
+  return parser.parseAttribute(attr);
+}
 static ParseResult parseCustomDirectiveAttrDict(OpAsmParser &parser,
                                                 NamedAttrList &attrs) {
   return parser.parseOptionalAttrDict(attrs);
@@ -759,7 +762,10 @@
   if (optAttribute)
     printer << ", " << optAttribute;
 }
-
+static void printCustomDirectiveSpacing(OpAsmPrinter &printer, Operation *op,
+                                        Attribute attribute) {
+  printer << attribute;
+}
 static void printCustomDirectiveAttrDict(OpAsmPrinter &printer, Operation *op,
                                          DictionaryAttr attrs) {
   printer.printOptionalAttrDict(attrs.getValue());
diff --git a/mlir/test/lib/Dialect/Test/TestOps.td b/mlir/test/lib/Dialect/Test/TestOps.td
--- a/mlir/test/lib/Dialect/Test/TestOps.td
+++ b/mlir/test/lib/Dialect/Test/TestOps.td
@@ -2315,6 +2315,16 @@
   }];
 }
 
+def FormatCustomDirectiveSpacing
+    : TEST_Op<"format_custom_directive_spacing"> {
+  let arguments = (ins StrAttr:$attr1, StrAttr:$attr2);
+  let assemblyFormat = [{
+    custom<CustomDirectiveSpacing>($attr1)
+    custom<CustomDirectiveSpacing>($attr2)
+    attr-dict
+  }];
+}
+
 def FormatCustomDirectiveAttrDict
     : TEST_Op<"format_custom_directive_attrdict"> {
   let arguments = (ins I64Attr:$attr, OptionalAttr<I64Attr>:$optAttr);
diff --git a/mlir/test/lib/Dialect/Test/TestTypeDefs.td b/mlir/test/lib/Dialect/Test/TestTypeDefs.td
--- a/mlir/test/lib/Dialect/Test/TestTypeDefs.td
+++ b/mlir/test/lib/Dialect/Test/TestTypeDefs.td
@@ -319,10 +319,17 @@
 def TestTypeCustom : Test_Type<"TestTypeCustom"> {
   let parameters = (ins "int":$a, OptionalParameter<"mlir::Optional<int>">:$b);
   let mnemonic = "custom_type";
-  let assemblyFormat = [{ `<` custom<CustomTypeA>($a)
+  let assemblyFormat = [{ `<` custom<CustomTypeA>($a) ``
                               custom<CustomTypeB>(ref($a), $b) `>` }];
 }
 
+def TestTypeCustomSpacing : Test_Type<"TestTypeCustomSpacing"> {
+  let parameters = (ins "int":$a, "int":$b);
+  let mnemonic = "custom_type_spacing";
+  let assemblyFormat = [{ `<` custom<CustomTypeA>($a)
+                              custom<CustomTypeA>($b) `>` }];
+}
+
 def TestTypeCustomString : Test_Type<"TestTypeCustomString"> {
   let parameters = (ins StringRefParameter<>:$foo);
   let mnemonic = "custom_type_string";
diff --git a/mlir/test/lib/Dialect/Test/TestTypes.cpp b/mlir/test/lib/Dialect/Test/TestTypes.cpp
--- a/mlir/test/lib/Dialect/Test/TestTypes.cpp
+++ b/mlir/test/lib/Dialect/Test/TestTypes.cpp
@@ -134,7 +134,7 @@
 }
 
 static void printBarString(AsmPrinter &printer, StringRef foo) {
-  printer << ' ' << foo;
+  printer << foo;
 }
 //===----------------------------------------------------------------------===//
 // Tablegen Generated Definitions
diff --git a/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir b/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir
--- a/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir
+++ b/mlir/test/mlir-tblgen/attr-or-type-format-roundtrip.mlir
@@ -62,6 +62,7 @@
 // CHECK: !test.default_valued_type<>
 // CHECK: !test.custom_type<-5>
 // CHECK: !test.custom_type<2 0 1 5>
+// CHECK: !test.custom_type_spacing<1 2>
 // CHECK: !test.custom_type_string<"foo" foo>
 // CHECK: !test.custom_type_string<"bar" bar>
 
@@ -98,6 +99,7 @@
   !test.default_valued_type<>,
   !test.custom_type<-5>,
   !test.custom_type<2 9 9 5>,
+  !test.custom_type_spacing<1 2>,
   !test.custom_type_string<"foo" foo>,
   !test.custom_type_string<"bar" bar>
 )
diff --git a/mlir/test/mlir-tblgen/op-format.mlir b/mlir/test/mlir-tblgen/op-format.mlir
--- a/mlir/test/mlir-tblgen/op-format.mlir
+++ b/mlir/test/mlir-tblgen/op-format.mlir
@@ -398,6 +398,9 @@
   return
 }
 
+// CHECK: test.format_custom_directive_spacing "a" "b"
+test.format_custom_directive_spacing "a" "b"
+
 // CHECK: test.format_literal_following_optional_group(5 : i32) : i32 {a}
 test.format_literal_following_optional_group(5 : i32) : i32 {a}
 
diff --git a/mlir/tools/mlir-tblgen/AttrOrTypeFormatGen.cpp b/mlir/tools/mlir-tblgen/AttrOrTypeFormatGen.cpp
--- a/mlir/tools/mlir-tblgen/AttrOrTypeFormatGen.cpp
+++ b/mlir/tools/mlir-tblgen/AttrOrTypeFormatGen.cpp
@@ -826,6 +826,12 @@
 
 void DefFormat::genCustomPrinter(CustomDirective *el, FmtContext &ctx,
                                  MethodBody &os) {
+  // Insert a space before the custom directive, if necessary.
+  if (shouldEmitSpace || !lastWasPunctuation)
+    os << tgfmt("$_printer << ' ';\n", &ctx);
+  shouldEmitSpace = true;
+  lastWasPunctuation = false;
+
   os << tgfmt("print$0($_printer", &ctx, el->getName());
   os.indent();
   for (FormatElement *arg : el->getArguments()) {