diff --git a/mypy/reachability.py b/mypy/reachability.py
index 5d170b5071db..132c269e96af 100644
--- a/mypy/reachability.py
+++ b/mypy/reachability.py
@@ -115,31 +115,44 @@ def infer_condition_value(expr: Expression, options: Options) -> int:
     MYPY_TRUE if true under mypy and false at runtime, MYPY_FALSE if
     false under mypy and true at runtime, else TRUTH_VALUE_UNKNOWN.
     """
+    if isinstance(expr, UnaryExpr) and expr.op == "not":
+        positive = infer_condition_value(expr.expr, options)
+        return inverted_truth_mapping[positive]
+
     pyversion = options.python_version
     name = ""
-    negated = False
-    alias = expr
-    if isinstance(alias, UnaryExpr):
-        if alias.op == "not":
-            expr = alias.expr
-            negated = True
+
     result = TRUTH_VALUE_UNKNOWN
     if isinstance(expr, NameExpr):
         name = expr.name
     elif isinstance(expr, MemberExpr):
         name = expr.name
-    elif isinstance(expr, OpExpr) and expr.op in ("and", "or"):
+    elif isinstance(expr, OpExpr):
+        if expr.op not in ("or", "and"):
+            return TRUTH_VALUE_UNKNOWN
+
         left = infer_condition_value(expr.left, options)
-        if (left in (ALWAYS_TRUE, MYPY_TRUE) and expr.op == "and") or (
-            left in (ALWAYS_FALSE, MYPY_FALSE) and expr.op == "or"
-        ):
-            # Either `True and <other>` or `False or <other>`: the result will
-            # always be the right-hand-side.
-            return infer_condition_value(expr.right, options)
-        else:
-            # The result will always be the left-hand-side (e.g. ALWAYS_* or
-            # TRUTH_VALUE_UNKNOWN).
-            return left
+        right = infer_condition_value(expr.right, options)
+        results = {left, right}
+        if expr.op == "or":
+            if ALWAYS_TRUE in results:
+                return ALWAYS_TRUE
+            elif MYPY_TRUE in results:
+                return MYPY_TRUE
+            elif left == right == MYPY_FALSE:
+                return MYPY_FALSE
+            elif results <= {ALWAYS_FALSE, MYPY_FALSE}:
+                return ALWAYS_FALSE
+        elif expr.op == "and":
+            if ALWAYS_FALSE in results:
+                return ALWAYS_FALSE
+            elif MYPY_FALSE in results:
+                return MYPY_FALSE
+            elif left == right == ALWAYS_TRUE:
+                return ALWAYS_TRUE
+            elif results <= {ALWAYS_TRUE, MYPY_TRUE}:
+                return MYPY_TRUE
+        return TRUTH_VALUE_UNKNOWN
     else:
         result = consider_sys_version_info(expr, pyversion)
         if result == TRUTH_VALUE_UNKNOWN:
@@ -155,8 +168,6 @@ def infer_condition_value(expr: Expression, options: Options) -> int:
             result = ALWAYS_TRUE
         elif name in options.always_false:
             result = ALWAYS_FALSE
-    if negated:
-        result = inverted_truth_mapping[result]
     return result
 
 
diff --git a/test-data/unit/check-unreachable-code.test b/test-data/unit/check-unreachable-code.test
index 6821b74b8b6d..368431127b76 100644
--- a/test-data/unit/check-unreachable-code.test
+++ b/test-data/unit/check-unreachable-code.test
@@ -481,25 +481,101 @@ import typing
 def make() -> bool: pass
 PY2 = PY3 = make()
 
-a = PY2 and 's'
-b = PY3 and 's'
-c = PY2 or 's'
-d = PY3 or 's'
-e = (PY2 or PY3) and 's'
-f = (PY3 or PY2) and 's'
-g = (PY2 or PY3) or 's'
-h = (PY3 or PY2) or 's'
+a = PY2 and str()
+b = PY3 and str()
+c = PY2 or str()
+d = PY3 or str()
+e = (PY2 or PY3) and str()
+f = (PY3 or PY2) and str()
+g = (PY2 or PY3) or str()
+h = (PY3 or PY2) or str()
 reveal_type(a)  # N: Revealed type is "builtins.bool"
-reveal_type(b)  # N: Revealed type is "Literal['s']"
-reveal_type(c)  # N: Revealed type is "Literal['s']"
+reveal_type(b)  # N: Revealed type is "builtins.str"
+reveal_type(c)  # N: Revealed type is "builtins.str"
 reveal_type(d)  # N: Revealed type is "builtins.bool"
-reveal_type(e)  # N: Revealed type is "Literal['s']"
-reveal_type(f)  # N: Revealed type is "Literal['s']"
+reveal_type(e)  # N: Revealed type is "builtins.str"
+reveal_type(f)  # N: Revealed type is "builtins.str"
 reveal_type(g)  # N: Revealed type is "builtins.bool"
 reveal_type(h)  # N: Revealed type is "builtins.bool"
 [builtins fixtures/ops.pyi]
 [out]
 
+[case testConditionalValuesBinaryOps]
+# flags: --platform linux
+import sys
+
+t_and_t = (sys.platform == 'linux' and sys.platform == 'linux') and str()
+t_or_t = (sys.platform == 'linux' or sys.platform == 'linux') and str()
+t_and_f = (sys.platform == 'linux' and sys.platform == 'windows') and str()
+t_or_f = (sys.platform == 'linux' or sys.platform == 'windows') and str()
+f_and_t = (sys.platform == 'windows' and sys.platform == 'linux') and str()
+f_or_t = (sys.platform == 'windows' or sys.platform == 'linux') and str()
+f_and_f = (sys.platform == 'windows' and sys.platform == 'windows') and str()
+f_or_f = (sys.platform == 'windows' or sys.platform == 'windows') and str()
+reveal_type(t_and_t) # N: Revealed type is "builtins.str"
+reveal_type(t_or_t) # N: Revealed type is "builtins.str"
+reveal_type(f_and_t) # N: Revealed type is "builtins.bool"
+reveal_type(f_or_t) # N: Revealed type is "builtins.str"
+reveal_type(t_and_f) # N: Revealed type is "builtins.bool"
+reveal_type(t_or_f) # N: Revealed type is "builtins.str"
+reveal_type(f_and_f) # N: Revealed type is "builtins.bool"
+reveal_type(f_or_f) # N: Revealed type is "builtins.bool"
+[builtins fixtures/ops.pyi]
+
+[case testConditionalValuesNegation]
+# flags: --platform linux
+import sys
+
+not_t = not sys.platform == 'linux' and str()
+not_f = not sys.platform == 'windows' and str()
+not_and_t = not (sys.platform == 'linux' and sys.platform == 'linux') and str()
+not_and_f = not (sys.platform == 'linux' and sys.platform == 'windows') and str()
+not_or_t = not (sys.platform == 'linux' or sys.platform == 'linux') and str()
+not_or_f = not (sys.platform == 'windows' or sys.platform == 'windows') and str()
+reveal_type(not_t) # N: Revealed type is "builtins.bool"
+reveal_type(not_f) # N: Revealed type is "builtins.str"
+reveal_type(not_and_t) # N: Revealed type is "builtins.bool"
+reveal_type(not_and_f) # N: Revealed type is "builtins.str"
+reveal_type(not_or_t) # N: Revealed type is "builtins.bool"
+reveal_type(not_or_f) # N: Revealed type is "builtins.str"
+[builtins fixtures/ops.pyi]
+
+[case testConditionalValuesUnsupportedOps]
+# flags: --platform linux
+import sys
+
+unary_minus = -(sys.platform == 'linux') and str()
+binary_minus = ((sys.platform == 'linux') - (sys.platform == 'linux')) and str()
+reveal_type(unary_minus) # N: Revealed type is "Union[Literal[0], builtins.str]"
+reveal_type(binary_minus) # N: Revealed type is "Union[Literal[0], builtins.str]"
+[builtins fixtures/ops.pyi]
+
+[case testMypyFalseValuesInBinaryOps_no_empty]
+# flags: --platform linux
+import sys
+from typing import TYPE_CHECKING
+
+MYPY = 0
+
+if TYPE_CHECKING and sys.platform == 'linux':
+    def foo1() -> int: ...
+if sys.platform == 'linux' and TYPE_CHECKING:
+    def foo2() -> int: ...
+if MYPY and sys.platform == 'linux':
+    def foo3() -> int: ...
+if sys.platform == 'linux' and MYPY:
+    def foo4() -> int: ...
+
+if TYPE_CHECKING or sys.platform == 'linux':
+    def bar1() -> int: ...  # E: Missing return statement
+if sys.platform == 'linux' or TYPE_CHECKING:
+    def bar2() -> int: ...  # E: Missing return statement
+if MYPY or sys.platform == 'linux':
+    def bar3() -> int: ...  # E: Missing return statement
+if sys.platform == 'linux' or MYPY:
+    def bar4() -> int: ...  # E: Missing return statement
+[builtins fixtures/ops.pyi]
+
 [case testShortCircuitAndWithConditionalAssignment]
 # flags: --platform linux
 import sys
diff --git a/test-data/unit/fixtures/ops.pyi b/test-data/unit/fixtures/ops.pyi
index df3b163166ad..67bc74b35c51 100644
--- a/test-data/unit/fixtures/ops.pyi
+++ b/test-data/unit/fixtures/ops.pyi
@@ -25,7 +25,7 @@ class tuple(Sequence[Tco]):
 class function: pass
 
 class str:
-    def __init__(self, x: 'int') -> None: pass
+    def __init__(self, x: 'int' = ...) -> None: pass
     def __add__(self, x: 'str') -> 'str': pass
     def __eq__(self, x: object) -> bool: pass
     def startswith(self, x: 'str') -> bool: pass

<!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.0 Transitional//EN' 'http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd'>
<html xmlns='http://www.w3.org/1999/xhtml'>
<head>
<title>pFad - Phonifier reborn</title>
<meta http-equiv='Content-Type' content='text/html; charset=utf-8' />
</head>
<body>
<h1>Pfad - The Proxy pFad of &#169; 2024 Garber Painting. All rights reserved.</h1>


<!-- Disclaimer -->
<p>Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.</p>
<br>
<p>Alternative Proxies:</p><p><a href="http://clevelandohioweatherforecast.com/php-proxy/index.php?q=https://patch-diff.githubusercontent.com/raw/python/mypy/pull/18944.diff" target="_blank">Alternative Proxy</a></p><p><a href="http://clevelandohioweatherforecast.com/pFad/index.php?u=https://patch-diff.githubusercontent.com/raw/python/mypy/pull/18944.diff" target="_blank">pFad Proxy</a></p><p><a href="http://clevelandohioweatherforecast.com/pFad/v3index.php?u=https://patch-diff.githubusercontent.com/raw/python/mypy/pull/18944.diff" target="_blank">pFad v3 Proxy</a></p><p><a href="http://clevelandohioweatherforecast.com/pFad/v4index.php?u=https://patch-diff.githubusercontent.com/raw/python/mypy/pull/18944.diff" target="_blank">pFad v4 Proxy</a></p></body>
</html>