diff --git a/apply.c b/apply.c
index 249248d4f205ca..fbb907d3c071a9 100644
--- a/apply.c
+++ b/apply.c
@@ -3893,7 +3893,7 @@ static int check_preimage(struct apply_state *state,
 		if (*ce && !(*ce)->ce_mode)
 			BUG("ce_mode == 0 for path '%s'", old_name);
 
-		if (trust_executable_bit || !S_ISREG(st->st_mode))
+		if (repo_trust_executable_bit(the_repository) || !S_ISREG(st->st_mode))
 			st_mode = ce_mode_from_stat(*ce, st->st_mode);
 		else if (*ce)
 			st_mode = (*ce)->ce_mode;
diff --git a/environment.c b/environment.c
index fc3ed8bb1c7a66..75069a884d663b 100644
--- a/environment.c
+++ b/environment.c
@@ -41,7 +41,6 @@
 static int pack_compression_seen;
 static int zlib_compression_seen;
 
-int trust_executable_bit = 1;
 int trust_ctime = 1;
 int check_stat = 1;
 int has_symlinks = 1;
@@ -142,6 +141,13 @@ int is_bare_repository(void)
 	return is_bare_repository_cfg && !repo_get_work_tree(the_repository);
 }
 
+int repo_trust_executable_bit(struct repository *repo)
+{
+	return repo->gitdir?
+		repo_config_values(repo)->trust_executable_bit :
+		1;
+}
+
 int have_git_dir(void)
 {
 	return startup_info->have_repository
@@ -305,7 +311,7 @@ int git_default_core_config(const char *var, const char *value,
 
 	/* This needs a better name */
 	if (!strcmp(var, "core.filemode")) {
-		trust_executable_bit = git_config_bool(var, value);
+		cfg->trust_executable_bit = git_config_bool(var, value);
 		return 0;
 	}
 	if (!strcmp(var, "core.trustctime")) {
@@ -720,5 +726,6 @@ void repo_config_values_init(struct repo_config_values *cfg)
 {
 	cfg->attributes_file = NULL;
 	cfg->apply_sparse_checkout = 0;
+	cfg->trust_executable_bit = 1;
 	cfg->branch_track = BRANCH_TRACK_REMOTE;
 }
diff --git a/environment.h b/environment.h
index 123a71cdc8d14e..44b97be654e0a3 100644
--- a/environment.h
+++ b/environment.h
@@ -91,6 +91,7 @@ struct repo_config_values {
 	/* section "core" config values */
 	char *attributes_file;
 	int apply_sparse_checkout;
+	int trust_executable_bit;
 
 	/* section "branch" config values */
 	enum branch_track branch_track;
@@ -123,6 +124,13 @@ int git_default_config(const char *, const char *,
 int git_default_core_config(const char *var, const char *value,
 			    const struct config_context *ctx, void *cb);
 
+/*
+ * Getters for the `repo_trust_executable_bit` fields of `struct repo_config_values`.
+ * They check `repo->gitdir` to prevent calling repo_config_values()
+ * before the configuration is loaded or in bare environments.
+ */
+int repo_trust_executable_bit(struct repository *repo);
+
 void repo_config_values_init(struct repo_config_values *cfg);
 
 /*
@@ -160,7 +168,6 @@ int is_bare_repository(void);
 extern char *git_work_tree_cfg;
 
 /* Environment bits from configuration mechanism */
-extern int trust_executable_bit;
 extern int trust_ctime;
 extern int check_stat;
 extern int has_symlinks;
diff --git a/read-cache.c b/read-cache.c
index 38a04b8de3d7fb..89f5c88c58ae27 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -202,15 +202,33 @@ void fill_stat_cache_info(struct index_state *istate, struct cache_entry *ce, st
 	}
 }
 
-static unsigned int st_mode_from_ce(const struct cache_entry *ce)
+/*
+ * Determine the appropriate index mode for a file based on its stat()
+ * information and the existing cache entry (if any).
+ *
+ * This function handles degradation for filesystems that lack
+ * symlink support or reliable executable bits.
+ */
+unsigned int ce_mode_from_stat(const struct cache_entry *ce, unsigned int mode)
 {
-	extern int trust_executable_bit, has_symlinks;
+	if (!has_symlinks && S_ISREG(mode) &&
+	    ce && S_ISLNK(ce->ce_mode))
+		return ce->ce_mode;
+	if (!repo_trust_executable_bit(the_repository) && S_ISREG(mode)) {
+		if (ce && S_ISREG(ce->ce_mode))
+			return ce->ce_mode;
+		return create_ce_mode(0666);
+	}
+	return create_ce_mode(mode);
+}
 
+static unsigned int st_mode_from_ce(const struct cache_entry *ce)
+{
 	switch (ce->ce_mode & S_IFMT) {
 	case S_IFLNK:
 		return has_symlinks ? S_IFLNK : (S_IFREG | 0644);
 	case S_IFREG:
-		return (ce->ce_mode & (trust_executable_bit ? 0755 : 0644)) | S_IFREG;
+		return (ce->ce_mode & (repo_trust_executable_bit(the_repository) ? 0755 : 0644)) | S_IFREG;
 	case S_IFGITLINK:
 		return S_IFDIR | 0755;
 	case S_IFDIR:
@@ -320,7 +338,7 @@ static int ce_match_stat_basic(const struct cache_entry *ce, struct stat *st)
 		/* We consider only the owner x bit to be relevant for
 		 * "mode changes"
 		 */
-		if (trust_executable_bit &&
+		if (repo_trust_executable_bit(the_repository) &&
 		    (0100 & (ce->ce_mode ^ st->st_mode)))
 			changed |= MODE_CHANGED;
 		break;
@@ -741,7 +759,7 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 		ce->ce_flags |= CE_INTENT_TO_ADD;
 
 
-	if (trust_executable_bit && has_symlinks) {
+	if (repo_trust_executable_bit(the_repository) && has_symlinks) {
 		ce->ce_mode = create_ce_mode(st_mode);
 	} else {
 		/* If there is an existing entry, pick the mode bits and type
diff --git a/read-cache.h b/read-cache.h
index 043da1f1aae706..3c4af2faeb5f78 100644
--- a/read-cache.h
+++ b/read-cache.h
@@ -5,20 +5,8 @@
 #include "object.h"
 #include "pathspec.h"
 
-static inline unsigned int ce_mode_from_stat(const struct cache_entry *ce,
-					     unsigned int mode)
-{
-	extern int trust_executable_bit, has_symlinks;
-	if (!has_symlinks && S_ISREG(mode) &&
-	    ce && S_ISLNK(ce->ce_mode))
-		return ce->ce_mode;
-	if (!trust_executable_bit && S_ISREG(mode)) {
-		if (ce && S_ISREG(ce->ce_mode))
-			return ce->ce_mode;
-		return create_ce_mode(0666);
-	}
-	return create_ce_mode(mode);
-}
+unsigned int ce_mode_from_stat(const struct cache_entry *ce,
+				unsigned int mode);
 
 static inline int ce_to_dtype(const struct cache_entry *ce)
 {