diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index 967b2eaf9b9..6cf40ac6cb8 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -335,6 +335,15 @@ identifier		{ident_start}{ident_cont}*
 typecast		"::"
 dot_dot			\.\.
 colon_equals	":="
+
+/*
+ * These operator-like tokens (unlike the above ones) also match the {operator}
+ * rule, which means that they might be overridden by a longer match if they
+ * are followed by a comment start or a + or - character. Accordingly, if you
+ * add to this list, you must also add corresponding code to the {operator}
+ * block to return the correct token in such cases. (This is not needed in
+ * psqlscan.l since the token value is ignored there.)
+ */
 equals_greater	"=>"
 less_equals		"<="
 greater_equals	">="
@@ -925,6 +934,25 @@ other			.
 						if (nchars == 1 &&
 							strchr(",()[].;:+-*/%^<>=", yytext[0]))
 							return yytext[0];
+						/*
+						 * Likewise, if what we have left is two chars, and
+						 * those match the tokens ">=", "<=", "=>", "<>" or
+						 * "!=", then we must return the appropriate token
+						 * rather than the generic Op.
+						 */
+						if (nchars == 2)
+						{
+							if (yytext[0] == '=' && yytext[1] == '>')
+								return EQUALS_GREATER;
+							if (yytext[0] == '>' && yytext[1] == '=')
+								return GREATER_EQUALS;
+							if (yytext[0] == '<' && yytext[1] == '=')
+								return LESS_EQUALS;
+							if (yytext[0] == '<' && yytext[1] == '>')
+								return NOT_EQUALS;
+							if (yytext[0] == '!' && yytext[1] == '=')
+								return NOT_EQUALS;
+						}
 					}
 
 					/*
diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l
index fe74abc1a6c..73eafebefec 100644
--- a/src/fe_utils/psqlscan.l
+++ b/src/fe_utils/psqlscan.l
@@ -296,6 +296,15 @@ identifier		{ident_start}{ident_cont}*
 typecast		"::"
 dot_dot			\.\.
 colon_equals	":="
+
+/*
+ * These operator-like tokens (unlike the above ones) also match the {operator}
+ * rule, which means that they might be overridden by a longer match if they
+ * are followed by a comment start or a + or - character. Accordingly, if you
+ * add to this list, you must also add corresponding code to the {operator}
+ * block to return the correct token in such cases. (This is not needed in
+ * psqlscan.l since the token value is ignored there.)
+ */
 equals_greater	"=>"
 less_equals		"<="
 greater_equals	">="
diff --git a/src/interfaces/ecpg/preproc/pgc.l b/src/interfaces/ecpg/preproc/pgc.l
index bc47c23d038..3645582b439 100644
--- a/src/interfaces/ecpg/preproc/pgc.l
+++ b/src/interfaces/ecpg/preproc/pgc.l
@@ -242,6 +242,15 @@ array			({ident_cont}|{whitespace}|[\[\]\+\-\*\%\/\(\)\>\.])*
 typecast		"::"
 dot_dot			\.\.
 colon_equals	":="
+
+/*
+ * These operator-like tokens (unlike the above ones) also match the {operator}
+ * rule, which means that they might be overridden by a longer match if they
+ * are followed by a comment start or a + or - character. Accordingly, if you
+ * add to this list, you must also add corresponding code to the {operator}
+ * block to return the correct token in such cases. (This is not needed in
+ * psqlscan.l since the token value is ignored there.)
+ */
 equals_greater	"=>"
 less_equals		"<="
 greater_equals	">="
@@ -729,6 +738,25 @@ cppline			{space}*#([^i][A-Za-z]*|{if}|{ifdef}|{ifndef}|{import})((\/\*[^*/]*\*+
 							if (nchars == 1 &&
 								strchr(",()[].;:+-*/%^<>=", yytext[0]))
 								return yytext[0];
+							/*
+							 * Likewise, if what we have left is two chars, and
+							 * those match the tokens ">=", "<=", "=>", "<>" or
+							 * "!=", then we must return the appropriate token
+							 * rather than the generic Op.
+							 */
+							if (nchars == 2)
+							{
+								if (yytext[0] == '=' && yytext[1] == '>')
+									return EQUALS_GREATER;
+								if (yytext[0] == '>' && yytext[1] == '=')
+									return GREATER_EQUALS;
+								if (yytext[0] == '<' && yytext[1] == '=')
+									return LESS_EQUALS;
+								if (yytext[0] == '<' && yytext[1] == '>')
+									return NOT_EQUALS;
+								if (yytext[0] == '!' && yytext[1] == '=')
+									return NOT_EQUALS;
+							}
 						}
 
 						base_yylval.str = mm_strdup(yytext);
diff --git a/src/test/regress/expected/create_operator.out b/src/test/regress/expected/create_operator.out
index 3a216c2ca8f..f3e41777318 100644
--- a/src/test/regress/expected/create_operator.out
+++ b/src/test/regress/expected/create_operator.out
@@ -37,6 +37,80 @@ CREATE OPERATOR => (
 ERROR:  syntax error at or near "=>"
 LINE 1: CREATE OPERATOR => (
                         ^
+-- lexing of <=, >=, <>, != has a number of edge cases
+-- (=> is tested elsewhere)
+-- this is legal because ! is not allowed in sql ops
+CREATE OPERATOR !=- (
+   leftarg = int8,		-- right unary
+   procedure = numeric_fac
+);
+SELECT 2 !=-;
+ ?column? 
+----------
+        2
+(1 row)
+
+-- make sure lexer returns != as <> even in edge cases
+SELECT 2 !=/**/ 1, 2 !=/**/ 2;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 2 !=-- comment to be removed by psql
+  1;
+ ?column? 
+----------
+ t
+(1 row)
+
+DO $$ -- use DO to protect -- from psql
+  declare r boolean;
+  begin
+    execute $e$ select 2 !=-- comment
+      1 $e$ into r;
+    raise info 'r = %', r;
+  end;
+$$;
+INFO:  r = t
+-- check that <= etc. followed by more operator characters are returned
+-- as the correct token with correct precedence
+SELECT true<>-1 BETWEEN 1 AND 1;  -- BETWEEN has prec. above <> but below Op
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT false<>/**/1 BETWEEN 1 AND 1;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT false<=-1 BETWEEN 1 AND 1;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT false>=-1 BETWEEN 1 AND 1;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT 2<=/**/3, 3>=/**/2, 2<>/**/3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ t        | t        | t
+(1 row)
+
+SELECT 3<=/**/2, 2>=/**/3, 2<>/**/2;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ f        | f        | f
+(1 row)
+
 -- Should fail. CREATE OPERATOR requires USAGE on SCHEMA
 BEGIN TRANSACTION;
 CREATE ROLE regress_rol_op1;
diff --git a/src/test/regress/expected/polymorphism.out b/src/test/regress/expected/polymorphism.out
index 68b88d33a16..f04c28e1c37 100644
--- a/src/test/regress/expected/polymorphism.out
+++ b/src/test/regress/expected/polymorphism.out
@@ -1478,6 +1478,42 @@ select dfunc('a'::text, 'b', flag => true); -- mixed notation
  a
 (1 row)
 
+-- this tests lexer edge cases around =>
+select dfunc(a =>-1);
+ dfunc 
+-------
+    -1
+(1 row)
+
+select dfunc(a =>+1);
+ dfunc 
+-------
+     1
+(1 row)
+
+select dfunc(a =>/**/1);
+ dfunc 
+-------
+     1
+(1 row)
+
+select dfunc(a =>--comment to be removed by psql
+  1);
+ dfunc 
+-------
+     1
+(1 row)
+
+-- need DO to protect the -- from psql
+do $$
+  declare r integer;
+  begin
+    select dfunc(a=>-- comment
+      1) into r;
+    raise info 'r = %', r;
+  end;
+$$;
+INFO:  r = 1
 -- check reverse-listing of named-arg calls
 CREATE VIEW dfview AS
    SELECT q1, q2,
diff --git a/src/test/regress/sql/create_operator.sql b/src/test/regress/sql/create_operator.sql
index 0e5d6356bc3..0579cb95e1d 100644
--- a/src/test/regress/sql/create_operator.sql
+++ b/src/test/regress/sql/create_operator.sql
@@ -41,6 +41,37 @@ CREATE OPERATOR => (
    procedure = numeric_fac
 );
 
+-- lexing of <=, >=, <>, != has a number of edge cases
+-- (=> is tested elsewhere)
+
+-- this is legal because ! is not allowed in sql ops
+CREATE OPERATOR !=- (
+   leftarg = int8,		-- right unary
+   procedure = numeric_fac
+);
+SELECT 2 !=-;
+-- make sure lexer returns != as <> even in edge cases
+SELECT 2 !=/**/ 1, 2 !=/**/ 2;
+SELECT 2 !=-- comment to be removed by psql
+  1;
+DO $$ -- use DO to protect -- from psql
+  declare r boolean;
+  begin
+    execute $e$ select 2 !=-- comment
+      1 $e$ into r;
+    raise info 'r = %', r;
+  end;
+$$;
+
+-- check that <= etc. followed by more operator characters are returned
+-- as the correct token with correct precedence
+SELECT true<>-1 BETWEEN 1 AND 1;  -- BETWEEN has prec. above <> but below Op
+SELECT false<>/**/1 BETWEEN 1 AND 1;
+SELECT false<=-1 BETWEEN 1 AND 1;
+SELECT false>=-1 BETWEEN 1 AND 1;
+SELECT 2<=/**/3, 3>=/**/2, 2<>/**/3;
+SELECT 3<=/**/2, 2>=/**/3, 2<>/**/2;
+
 -- Should fail. CREATE OPERATOR requires USAGE on SCHEMA
 BEGIN TRANSACTION;
 CREATE ROLE regress_rol_op1;
diff --git a/src/test/regress/sql/polymorphism.sql b/src/test/regress/sql/polymorphism.sql
index 45ae7a23aa7..5cdfcd2e69c 100644
--- a/src/test/regress/sql/polymorphism.sql
+++ b/src/test/regress/sql/polymorphism.sql
@@ -785,6 +785,21 @@ select dfunc('a'::text, 'b', flag => false); -- mixed notation
 select dfunc('a'::text, 'b', true); -- full positional notation
 select dfunc('a'::text, 'b', flag => true); -- mixed notation
 
+-- this tests lexer edge cases around =>
+select dfunc(a =>-1);
+select dfunc(a =>+1);
+select dfunc(a =>/**/1);
+select dfunc(a =>--comment to be removed by psql
+  1);
+-- need DO to protect the -- from psql
+do $$
+  declare r integer;
+  begin
+    select dfunc(a=>-- comment
+      1) into r;
+    raise info 'r = %', r;
+  end;
+$$;
 
 -- check reverse-listing of named-arg calls
 CREATE VIEW dfview AS